European Resuscitation Council Guidelines for Resuscitation 2010-3
Resuscitation81(2010)1293–1304
Contents lists available at ScienceDirect
Resuscitation
j o u r n a l h o m e p a g e:w w w.e l s e v i e r.c o m/l o c a t e/r e s u s c i t a t i o
n
European Resuscitation Council Guidelines for Resuscitation2010
Section3.Electrical therapies:Automated external de?brillators,de?brillation, cardioversion and pacing
Charles D.Deakin a,?,Jerry P.Nolan b,Kjetil Sunde c,Rudolph W.Koster d
a Southampton University Hospital NHS Trust,Southampton,UK
b Royal United Hospital,Bath,UK
c Oslo University Hospital Ulleval,Oslo,Norway
d Department of Cardiology,Academic Medical Center,Amsterdam,Th
e Netherlands
Summary of changes since2005Guidelines
The most important changes in the2010European Resuscitation Council(ERC)guidelines for electrical therapies include:
?The importance of early,uninterrupted chest compressions is emphasised throughout these guidelines.
?Much greater emphasis on minimising the duration of the pre-shock and post-shock pauses.The continuation of compressions during charging of the de?brillator is recommended.?Immediate resumption of chest compressions following de?b-rillation is also emphasised;in combination with continuation of compressions during de?brillator charging,the delivery of de?brillation should be achievable with an interruption in chest compressions of no more than5s.
?Safety of the rescuer remains paramount,but there is recogni-tion in these guidelines that the risk of harm to a rescuer from a de?brillator is very small,particularly if the rescuer is wearing gloves.The focus is now on a rapid safety check to minimise the pre-shock pause.
?When treating out-of-hospital cardiac arrest,emergency med-ical services(EMS)personnel should provide good-quality CPR while a de?brillator is retrieved,applied and charged,but rou-tine delivery of a pre-speci?ed period of CPR(e.g.,2or3min) before rhythm analysis and a shock is delivered is no longer recommended.For some emergency medical services that have already fully implemented a pre-speci?ed period of chest com-pressions before de?brillation,given the lack of convincing data either supporting or refuting this strategy,it is reasonable for them to continue this practice.
?The use of up to three-stacked shocks may be considered if ventricular?brillation/pulseless ventricular tachycardia(VF/VT)
?Corresponding author.
E-mail address:charlesdeakin@https://www.360docs.net/doc/08620125.html,(C.D.Deakin).
occurs during cardiac catheterisation or in the early post-operative period following cardiac surgery.This three-shock strategy may also be considered for an initial,witnessed VF/VT cardiac arrest when the patient is already connected to a manual de?brillator.
?Electrode pastes and gels can spread between the two paddles, creating the potential for a spark and should not be used Introduction
The chapter presents guidelines for de?brillation using both automated external de?brillators(AEDs)and manual de?brillators. There are only a few differences from the2005ERC Guidelines.All healthcare providers and lay responders can use AEDs as an inte-gral component of basic life support.Manual de?brillation is used as part of advanced life support(ALS)therapy.Synchronised car-dioversion and pacing options are included on many de?brillators and are also discussed in this chapter.
De?brillation is the passage of an electrical current across the myocardium of suf?cient magnitude to depolarise a critical mass of myocardium and enable restoration of coordinated electrical activity.De?brillation is de?ned as the termination of?brillation or,more precisely,the absence of VF/VT at5s after shock deliv-ery;however,the goal of attempted de?brillation is to restore an organised rhythm and a spontaneous circulation.
De?brillator technology is advancing rapidly.AED interaction with the rescuer through voice prompts is now established and future technology may enable more speci?c instructions to be given by voice prompt.The evolving ability of de?brillators to assess the rhythm whilst CPR is in progress is an important advance and enables rescuers to assess the rhythm without interrupting exter-nal chest compressions.In the future,waveform analysis may also enable the de?brillator to calculate the optimal time at which to give a shock.
0300-9572/$–see front matter?2010European Resuscitation Council.Published by Elsevier Ireland Ltd.All rights reserved. doi:10.1016/j.resuscitation.2010.08.008
1294 C.D.Deakin et al./Resuscitation81(2010)1293–1304
A vital link in the Chain of Survival
De?brillation is a key link in the Chain of Survival and is one of the few interventions that have been shown to improve out-come from VF/VT cardiac arrest.The previous guidelines published in2005rightly emphasized the importance of early de?brillation with minimum delay.1,2
The probability of successful de?brillation and subsequent sur-vival to hospital discharge declines rapidly with time3,4and the ability to deliver early de?brillation is one of the most impor-tant factors in determining survival from cardiac arrest.For every minute delay in de?brillation,in the absence of bystander CPR,sur-vival from witnessed VF decreases by10–12%.4,5EMS systems do not generally have the capability to deliver de?brillation through traditional paramedic responders within the?rst few minutes of a call and the alternative use of trained lay responders to deliver prompt de?brillation using AEDs is now widespread.EMS sys-tems that have reduced time to de?brillation following cardiac arrest using trained lay responders have reported greatly improved survival to hospital discharge rates,6–9some as high as75%if de?b-rillation is performed within3min of collapse.10This concept has also been extended to in-hospital cardiac arrests where staff,other than doctors,are also being trained to de?brillate using an AED before arrival of the cardiac arrest team.11
When bystander CPR is provided,the fall in survival is more gradual and averages3–4%per minute from collapse to de?brillation3,4,12;bystander CPR can double3,4,13or triple14sur-vival from witnessed out-of-hospital cardiac arrest.Resuscitation instructions given by the ambulance service before the arrival of trained help increase the quantity and quality of bystander CPR15,16 and use of video instructions by phone may improve performance further.17,18
All healthcare providers with a duty to perform CPR should be trained,equipped,and encouraged to perform de?brillation and CPR.Early de?brillation should be available throughout all hospi-tals,outpatient medical facilities and public areas of mass gathering (see Section2).19Those trained in the use of an AED should also be trained to deliver high-quality CPR before arrival of ALS providers so that the effectiveness of early de?brillation can be optimised. Automated external de?brillators
Automated external de?brillators are sophisticated,reliable computerised devices that use voice and visual prompts to guide lay rescuers and healthcare professionals to safely attempt de?b-rillation in cardiac arrest victims.Some AEDs combine guidance for de?brillation with guidance for the delivery of optimal chest https://www.360docs.net/doc/08620125.html,e of AEDs by lay or non-healthcare rescuers is covered in Section2.19
In many situations,an AED is used to provide initial de?brillation but is subsequently swapped for a manual de?brillator on arrival of EMS personnel.If such a swap is done without considering the phase the AED cycle is in,the next shock may be delayed,which may compromise outcome.20For this reason,EMS personnel should leave the AED connected while securing airway and IV access.The AED should be left attached for the next rhythm analysis and,if indicated,a shock delivered before the AED is swapped for a manual de?brillator.
Currently many manufacturers use product-speci?c electrode to de?brillator connectors,which necessitates the de?brillation pads also being removed and replaced with a pair compatible with the new de?brillator.Manufacturers are encouraged to collaborate and develop a universal connector that enables all de?brillation pads to be compatible with all de?brillators.This will have signi?cant patient bene?t and minimise unnecessary waste.In-hospital use of AEDs
At the time of the2010Consensus on CPR Science Conference there were no published randomised trials comparing in-hospital use of AEDs with manual de?brillators.Two lower level studies of adults with in-hospital cardiac arrest from shockable rhythms showed higher survival to hospital discharge rates when de?b-rillation was provided through an AED programme than with manual de?brillation alone.21,22One retrospective study23demon-strated no improvements in survival to hospital discharge for in-hospital adult cardiac arrest when using an AED compared with manual de?brillation.In this study,patients in the AED group with initial asystole or pulseless electrical activity(PEA)had a lower survival to hospital discharge rate compared with those in the manual de?brillator group(15%versus23%;p=0.04).A manikin study showed that use of an AED signi?cantly increased the likelihood of delivering three shocks but increased the time to deliver the shocks when compared with manual de?brillators.24 In contrast,a study of mock arrests in simulated patients showed that use of monitoring leads and fully automated de?brilla-tors reduced time to de?brillation when compared with manual de?brillators.25
Delayed de?brillation may occur when patients sustain car-diac arrest in unmonitored hospital beds and in outpatient departments.26In these areas several minutes may elapse before resuscitation teams arrive with a de?brillator and deliver shocks. Despite limited evidence,AEDs should be considered for the hospi-tal setting as a way to facilitate early de?brillation(a goal of<3min from collapse),especially in areas where healthcare providers have no rhythm recognition skills or where they use de?brillators infre-quently.An effective system for training and retraining should be in place.11Enough healthcare providers should be trained to enable achievement of the goal of providing the?rst shock within3min of collapse anywhere in the hospital.Hospitals should monitor collapse-to-?rst shock intervals and monitor resuscitation out-comes.
Shock in manual versus semi-automatic mode
Many AEDs can be operated in both manual and semi-automatic mode but few studies have compared these two options.The semi-automatic mode has been shown to reduce time to?rst shock when used both in-hospital27and pre-hospital28settings,and results in higher VF conversion rates,28and delivery of fewer inappro-priate shocks.29Conversely,semi-automatic modes result in less time spent performing chest compressions29,30mainly because of a longer pre-shock pause associated with automated rhythm anal-ysis.Despite these differences,no overall difference in return of spontaneous circulation(ROSC),survival,or discharge rate from hospital has been demonstrated in any study.23,27,28The de?brilla-tion mode that affords the best outcome will depend on the system, skills,training and ECG recognition skills of rescuers.A shorter pre-shock pause and lower total hands-off-ratio increases vital organ perfusion and the probability of ROSC.31–33With manual de?bril-lators and some AEDs it is possible to perform chest compressions during charging and thereby reduce the pre-shock pause to less than5s.Trained individuals may deliver de?brillation in manual mode but frequent team training and ECG recognition skills are essential.
Automated rhythm analysis
Automated external de?brillators have microprocessors that analyse several features of the ECG,including frequency and ampli-tude.Developing technology should soon enable AEDs to provide information about frequency and depth of chest compressions dur-
C.D.Deakin et al./Resuscitation81(2010)1293–13041295
ing CPR that may improve basic life support(BLS)performance by all rescuers.34,35
Automated external de?brillators have been tested extensively against libraries of recorded cardiac rhythms and in many trials in adults36,37and children.38,39They are extremely accurate in rhythm analysis.Although most AEDs are not designed to deliver synchronised shocks,all AEDs will recommend shocks for VT if the rate and R-wave morphology and duration exceeds preset values. Most AEDs require a‘hands-off’period while the device analyses the rhythm.This‘hands-off’period results in interruption to chest compressions for varying but signi?cant periods of time40;a factor shown to have signi?cant adverse impact on outcome from car-diac arrest.41Manufacturers of these devices should make every effort to develop software that minimises this analysis period to ensure that interruptions to external chest compressions are kept to a minimum.
Strategies before de?brillation
Minimising the pre-shock pause
The delay between stopping chest compressions and delivery of the shock(the pre-shock pause)must be kept to an absolute mini-mum;even5–10s delay will reduce the chances of the shock being successful.31,32,42The pre-shock pause can easily be reduced to less than5s by continuing compressions during charging of the de?b-rillator and by having an ef?cient team coordinated by a leader who communicates effectively.The safety check to ensure that nobody is in contact with the patient at the moment of de?bril-lation should be undertaken rapidly but ef?ciently.The negligible risk of a rescuer receiving an accidental shock is minimised even further if all rescuers wear gloves.43The post-shock pause is min-imised by resuming chest compressions immediately after shock delivery(see below).The entire process of de?brillation should be achievable with no more than a5s interruption to chest compres-sion.
Safe use of oxygen during de?brillation
In an oxygen-enriched atmosphere,sparking from poorly applied de?brillator paddles can cause a?re.44–49There are several reports of?res being caused in this way and most have resulted in signi?cant burns to the patient.There are no case reports of ?res caused by sparking where de?brillation was delivered using adhesive pads.In two manikin studies the oxygen concentration in the zone of de?brillation was not increased when ventilation devices(bag-valve device,self-in?ating bag,modern intensive care unit ventilator)were left attached to a tracheal tube or the oxygen source was vented at least1m behind the patient’s mouth.50,51One study described higher oxygen concentrations and longer washout periods when oxygen is administered in con?ned spaces without adequate ventilation.52
The risk of?re during attempted de?brillation can be minimised by taking the following precautions:
?Take off any oxygen mask or nasal cannulae and place them at least1m away from the patient’s chest.
?Leave the ventilation bag connected to the tracheal tube or supra-glottic airway device.Alternatively,disconnect any bag-valve device from the tracheal tube or supraglottic airway device and remove it at least1m from the patient’s chest during de?brilla-tion.
?If the patient is connected to a ventilator,for example in the operating room or critical care unit,leave the ventilator tubing (breathing circuit)connected to the tracheal tube unless chest
compressions prevent the ventilator from delivering adequate tidal volumes.In this case,the ventilator is usually substituted by a ventilation bag,which can itself be left connected or detached and removed to a distance of at least1m.If the ventilator tub-ing is disconnected,ensure it is kept at least1m from the patient or,better still,switch the ventilator off;modern ventilators gen-erate massive oxygen?ows when disconnected.During normal use,when connected to a tracheal tube,oxygen from a ventilator in the critical care unit will be vented from the main ventilator housing well away from the de?brillation zone.Patients in the critical care unit may be dependent on positive end expiratory pressure(PEEP)to maintain adequate oxygenation;during car-dioversion,when the spontaneous circulation potentially enables blood to remain well oxygenated,it is particularly appropriate to leave the critically ill patient connected to the ventilator during shock delivery.
?Minimise the risk of sparks during de?brillation.Self-adhesive de?brillation pads are less likely to cause sparks than manual paddles.
Some early versions of the LUCAS external chest compression device are driven by high?ow rates of oxygen which discharges waste gas over the patient’s chest.High ambient levels of oxygen over the chest have been documented using this device,particularly in relatively con?ned spaces such as the back of the ambulance and caution should be used when de?brillating patients while using the oxygen-powered model.52
The technique for electrode contact with the chest
Optimal de?brillation technique aims to deliver current across the?brillating myocardium in the presence of minimal transtho-racic impedance.Transthoracic impedance varies considerably with body mass,but is approximately70–80 in adults.53,54The techniques described below aim to place external electrodes(pad-dles or self-adhesive pads)in an optimal position using techniques that minimise transthoracic impedance.
Shaving the chest
Patients with a hairy chest have poor electrode-to-skin electri-cal contact and air trapping beneath the electrode.This causes high impedance,reduced de?brillation ef?cacy,risk of arcing(sparks) from electrode-to-skin and electrode to electrode and is more likely to cause burns to the patient’s chest.Rapid shaving of the area of intended electrode placement may be necessary,but do not delay de?brillation if a shaver is not immediately available. Shaving the chest per se may reduce transthoracic impedance slightly and has been recommended for elective DC cardioversion with monophasic de?brillators,55although the ef?cacy of biphasic impedance-compensated waveforms may not be so susceptible to higher transthoracic impedance.56
Paddle force
If using paddles,apply them?rmly to the chest wall.This reduces transthoracic impedance by improving electrical contact at the electrode–skin interface and reducing thoracic volume.57 The de?brillator operator should always press?rmly on handheld electrode paddles,the optimal force being8kg in adult and5kg in children1–8years using adult paddles.58Eight kilogram force may be attainable only by the strongest members of the cardiac arrest team and therefore it is recommended that these individuals apply the paddles during de?brillation.Unlike self-adhesive pads,manual paddles have a bare metal plate that requires a conductive material placed between the metal and patient’s skin to improve electrical
1296 C.D.Deakin et al./Resuscitation81(2010)1293–1304
https://www.360docs.net/doc/08620125.html,e of bare-metal paddles alone creates high transthoracic impedance and is likely to increase the risk of arcing and worsen cutaneous burns from de?brillation.
Electrode position
No human studies have evaluated the electrode position as a determinant of ROSC or survival from VF/VT cardiac arrest.Trans-myocardial current during de?brillation is likely to be maximal when the electrodes are placed so that the area of the heart that is?brillating lies directly between them(i.e.ventricles in VF/VT, atria in AF).Therefore,the optimal electrode position may not be the same for ventricular and atrial arrhythmias.
More patients are presenting with implantable medical devices (e.g.,permanent pacemaker,implantable cardioverter de?brillator (ICD)).Medic Alert bracelets are recommended for these patients. These devices may be damaged during de?brillation if current is discharged through electrodes placed directly over the device.59,60 Place the electrode away from the device(at least8cm)59or use an alternative electrode position(anterior-lateral,anterior-posterior) as described below.
Transdermal drug patches may prevent good electrode contact, causing arcing and burns if the electrode is placed directly over the patch during de?brillation.61,62Remove medication patches and wipe the area before applying the electrode.
Placement for ventricular arrhythmias and cardiac arrest Place electrodes(either pads or paddles)in the conventional sternal-apical position.The right(sternal)electrode is placed to the right of the sternum,below the clavicle.The apical pad-dle is placed in the left mid-axillary line,approximately level with the V6ECG electrode or female breast.This position should be clear of any breast tissue.It is important that this electrode is placed suf?ciently laterally.Other acceptable pad positions include
?Placement of each electrode on the lateral chest walls,one on the right and the other on the left side(bi-axillary).
?One electrode in the standard apical position and the other on the right upper back.
?One electrode anteriorly,over the left precordium,and the other electrode posteriorly to the heart just inferior to the left scapula.
It does not matter which electrode(apex/sternum)is placed in either position.
Transthoracic impedance has been shown to be minimised when the apical electrode is not placed over the female breast.63 Asymmetrically shaped apical electrodes have a lower impedance when placed longitudinally rather than transversely.64 Placement for atrial arrhythmias
Atrial?brillation is maintained by functional re-entry circuits anchored in the left atrium.As the left atrium is located pos-teriorly in the thorax,electrode positions that result in a more posterior current pathway may theoretically be more effective for atrial arrhythmias.Although some studies have shown that antero-posterior electrode placement is more effective than the traditional antero-apical position in elective cardioversion of atrial ?brillation,65,66the majority have failed to demonstrate any clear advantage of any speci?c electrode position.67,68Ef?cacy of car-dioversion may be less dependent on electrode position when using biphasic impedance-compensated waveforms.56The following electrode positions all appear safe and effective for cardioversion of atrial arrhythmias:?Traditional antero-apical position.
?Antero-posterior position(one electrode anteriorly,over the left precordium,and the other electrode posteriorly to the heart just inferior to the left scapula).
Respiratory phase
Transthoracic impedance varies during respiration,being min-imal at end-expiration.If possible,de?brillation should be attempted at this phase of the respiratory cycle.Positive end expira-tory pressure(PEEP)increases transthoracic impedance and should be minimised during de?brillation.Auto-PEEP(gas trapping)may be particularly high in asthmatics and may necessitate higher than usual energy levels for de?brillation.69
Electrode size
The Association for the Advancement of Medical Instrumen-tation recommends a minimum electrode size of for individual electrodes and the sum of the electrode areas should be a minimum of150cm2.70Larger electrodes have lower impedance,but exces-sively large electrodes may result in less transmyocardial current ?ow.71
For adult de?brillation,both handheld paddle electrodes and self-adhesive pad electrodes8–12cm in diameter are used and function well.De?brillation success may be higher with electrodes of12cm diameter compared with those of8cm diameter.54,72 Standard AEDs are suitable for use in children over the age of8 years.In children between1and8years use paediatric pads with an attenuator to reduce delivered energy or a paediatric mode if they are available;if not,use the unmodi?ed machine,taking care to ensure that the adult pads do not https://www.360docs.net/doc/08620125.html,e of AEDs is not recommended in children less than1year.
Coupling agents
If using manual paddles,disposable gel pads should be used to reduce impedance at the electrode–skin interface.Electrode pastes and gels can spread between the two paddles,creating the potential for a spark and should not be used.Do not use bare electrodes with-out gel pads because the resultant high transthoracic impedance may impair the effectiveness of de?brillation,increase the sever-ity of any cutaneous burns and risk arcing with subsequent?re or explosion.
Pads versus paddles
Self-adhesive de?brillation pads have practical bene?ts over paddles for routine monitoring and de?brillation.73–77They are safe and effective and are preferable to standard de?brillation paddles.72Consideration should be given to use of self-adhesive pads in peri-arrest situations and in clinical situations where patient access is dif?cult.They have a similar transthoracic impedance71(and therefore ef?cacy)78,79to manual paddles and enable the operator to de?brillate the patient from a safe distance rather than leaning over the patient as occurs with paddles.When used for initial monitoring of a rhythm,both pads and paddles enable quicker delivery of the?rst shock compared with standard ECG electrodes,but pads are quicker than paddles.80
When gel pads are used with paddles,the electrolyte gel becomes polarised and thus is a poor conductor after de?brillation. This can cause spurious asystole that may persist for3–4min when used to monitor the rhythm;a phenomenon not reported with self-adhesive pads.74,81When using a gel pad/paddle combination con?rm a diagnosis of asystole with independent ECG electrodes rather than the paddles.
C.D.Deakin et al./Resuscitation81(2010)1293–13041297
Fibrillation waveform analysis
It is possible to predict,with varying reliability,the success of de?brillation from the?brillation waveform.82–101If optimal de?b-rillation waveforms and the optimal timing of shock delivery can be determined in prospective studies,it should be possible to pre-vent the delivery of unsuccessful high energy shocks and minimise myocardial injury.This technology is under active development and investigation but current sensitivity and speci?city is insuf-?cient to enable introduction of VF waveform analysis into clinical practice.
CPR versus de?brillation as the initial treatment
A number of studies have examined whether a period of CPR prior to de?brillation is bene?cial,particularly in patients with an unwitnessed arrest or prolonged collapse without resuscita-tion.A review of evidence for the2005guidelines resulted in the recommendation that it was reasonable for EMS personnel to give a period of about2min of CPR(i.e.about?ve cycles at30:2)before de?brillation in patients with prolonged collapse (>5min).1This recommendation was based on clinical studies where response times exceeded4–5min,a period of1.5–3min of CPR by paramedics or EMS physicians before shock delivery improved ROSC,survival to hospital discharge102,103and one year survival103for adults with out-of-hospital VF/VT compared with immediate de?brillation.In some animal studies of VF lasting at least5min,CPR before de?brillation improved haemodynamics and survival.103–106A recent ischaemic swine model of cardiac arrest showed a decreased survival after pre-shock CPR.107 In contrast,two randomized controlled trials,a period of 1.5–3min of CPR by EMS personnel before de?brillation did not improve ROSC or survival to hospital discharge in patients with out-of-hospital VF/VT,regardless of EMS response interval.108,109Four other studies have also failed to demonstrate signi?cant improve-ments in overall ROSC or survival to hospital discharge with an initial period of CPR,102,103,110,111although one did show a higher rate of favourable neurological outcome at30days and one year after cardiac arrest.110
The duration of collapse is frequently dif?cult to estimate accu-rately and there is evidence that performing chest compressions while retrieving and charging a de?brillator improves the proba-bility of survival.112For these reasons,in any cardiac arrest they have not witnessed,EMS personnel should provide good-quality CPR while a de?brillator is retrieved,applied and charged,but rou-tine delivery of a pre-speci?ed period of CPR(e.g.,2or3min)before rhythm analysis and a shock is delivered is not recommended. Some EMS systems have already fully implemented a pre-speci?ed period of chest compressions before de?brillation;given the lack of convincing data either supporting or refuting this strategy,it is reasonable for them to continue this practice.
In hospital environments,settings with an AED on-site and available(including lay responders),or EMS-witnessed events, de?brillation should be performed as soon as the de?brillator is available.Chest compressions should be performed until just before the de?brillation attempt(see Section4advanced life support).113
The importance of early,uninterrupted chest compressions is emphasised throughout these guidelines.In practice,it is often dif-?cult to ascertain the exact time of collapse and,in any case,CPR should be started as soon as possible.The rescuer providing chest compressions should interrupt chest compressions only for ven-tilations,rhythm analysis and shock delivery,and should resume chest compressions as soon as a shock is delivered.When two res-cuers are present,the rescuer operating the AED should apply the electrodes whilst CPR is in progress.Interrupt CPR only when it is necessary to assess the rhythm and deliver a shock.The AED oper-ator should be prepared to deliver a shock as soon as analysis is complete and the shock is advised,ensuring no rescuer is in contact with the victim.
Delivery of de?brillation
One-shock versus three-stacked shock sequence
A major change in the2005guidelines was the recommendation to give single rather than three-stacked shocks.This was because animal studies had shown that relatively short interruptions in external chest compression to deliver rescue breaths114,115or per-form rhythm analysis33were associated with post-resuscitation myocardial dysfunction and reduced survival.Interruptions in external chest compression also reduced the chances of converting VF to another rhythm.32Analysis of CPR performance during out-of-hospital34,116and in-hospital35cardiac arrest also showed that signi?cant interruptions were common,with chest compressions comprising no more than51–76%34,35of total CPR time.
With?rst shock ef?cacy of biphasic waveforms generally exceeding90%,117–120failure to cardiovert VF successfully is more likely to suggest the need for a period of CPR rather than a further shock.Even if the de?brillation attempt is successful in restoring a perfusing rhythm,it is very rare for a pulse to be palpable immedi-ately after de?brillation and the delay in trying to palpate a pulse will further compromise the myocardium if a perfusing rhythm has not been restored.40
Subsequent studies have shown a signi?cantly lower hands-off-ratio with the one-shock protocol121and some,41,122,123but not all,121,124have suggested a signi?cant survival bene?t from this single-shock strategy.However,all studies except one124were before-after studies and all introduced multiple changes in the pro-tocol,making it dif?cult to attribute a possible survival bene?t to one of the changes.
When de?brillation is warranted,give a single shock and resume chest compressions immediately following the shock.Do not delay CPR for rhythm reanalysis or a pulse check immediately after a shock.Continue CPR(30compressions:2ventilations)for2min until rhythm reanalysis is undertaken and another shock given(if indicated)(see Section4advanced life support).113This single-shock strategy is applicable to both monophasic and biphasic de?brillators.
If VF/VT occurs during cardiac catheterisation or in the early post-operative period following cardiac surgery(when chest com-pressions could disrupt vascular sutures),consider delivering up to three-stacked shocks before starting chest compressions(see Section8special circumstances).125This three-shock strategy may also be considered for an initial,witnessed VF/VT cardiac arrest if the patient is already connected to a manual de?brillator.Although there are no data supporting a three-shock strategy in any of these circumstances,it is unlikely that chest compressions will improve the already very high chance of return of spontaneous circulation when de?brillation occurs early in the electrical phase,immedi-ately after onset of VF.
Waveforms
Historically,de?brillators delivering a monophasic pulse had been the standard of care until the1990s.Monophasic de?brillators deliver current that is unipolar(i.e.one direction of current?ow) (Fig.3.1).Monophasic de?brillators were particularly susceptible to waveform modi?cation depending on transthoracic impedance. Small patients with minimal transthoracic impedance received considerably greater transmyocardial current than larger patients,
1298 C.D.Deakin et al./Resuscitation 81(2010)
1293–1304
Fig.3.1.Monophasic damped sinusoidal waveform (MDS).
where not only was the current less,but the waveform lengthened to the extent that its ef?cacy was reduced.
Monophasic de?brillators are no longer manufactured,and although many will remain in use for several years,biphasic de?b-rillators have now superseded them.Biphasic de?brillators deliver current that ?ows in a positive direction for a speci?ed duration before reversing and ?owing in a negative direction for the remain-ing milliseconds of the electrical discharge.There are two main types of biphasic waveform:the biphasic truncated exponential (BTE)(Fig.3.2)and rectilinear biphasic (RLB)(Fig.3.3).Biphasic de?brillators compensate for the wide variations in transthoracic impedance by electronically adjusting the waveform magnitude and duration to ensure optimal current delivery to the myocardium,irrespective of the patient’s size.
A pulsed biphasic waveform has recently been described in which the current rapidly oscillates between baseline and a pos-itive value before inverting in a negative pattern.This waveform is also in clinical use.It may have a similar ef?cacy as other biphasic waveforms,but the single clinical study of this waveform was not performed with an impedance compensating device.126,127There are several other different biphasic waveforms,all with no clini-cal evidence of superiority for any individual waveform compared with another.
All manual de?brillators and AEDs that allow manual override of energy levels should be labelled to indicate their waveform (monophasic or biphasic)and recommended energy levels for attempted de?brillation of
VF/VT.
Fig.3.2.Biphasic truncated exponential waveform
(BTE).
Fig.3.3.Rectilinear biphasic waveform (RLB).
Monophasic versus biphasic de?brillation
Although biphasic waveforms are more effective at terminating ventricular arrhythmias at lower energy levels,have demonstrated greater ?rst shock ef?cacy than monophasic waveforms,and have greater ?rst shock ef?cacy for long duration VF/VT,128–130no randomised studies have demonstrated superiority in terms of neu-rologically intact survival to hospital discharge.
Some,119,128–133but not all,134studies suggest the biphasic waveform improves short-term outcomes of VF termination com-pared with monophasic de?brillation.
Biphasic waveforms have been shown to be superior to monophasic waveforms for elective cardioversion of atrial ?bril-lation,with greater overall success rates,using less cumulative energy and reducing the severity of cutaneous burns,135–138and are the waveform of choice for this procedure.Multiphasic versus biphasic de?brillation
A number of multiphasic waveforms (e.g.triphasic,quadripha-sic,multiphasic)have also been trialled in animal studies.Animal data suggest that multiphasic waveforms may de?brillate at lower energies and induce less post-shock myocardial dysfunction.139–141These results are limited by studies of short duration of VF (approx-imately 30s)and lack of human studies for validation.At present,there are no human studies comparing a multiphasic waveform with biphasic waveforms for de?brillation and no de?brillator cur-rently available uses multiphasic waveforms.Energy levels
De?brillation requires the delivery of suf?cient electrical energy to de?brillate a critical mass of myocardium,abolish the wavefronts of VF and enable restoration of spontaneous synchronized electrical activity in the form of an organised rhythm.The optimal energy for de?brillation is that which achieves de?brillation whilst causing the minimum of myocardial damage.142Selection of an appropriate energy level also reduces the number of repetitive shocks,which in turn limits myocardial damage.143
Optimal energy levels for both monophasic and biphasic wave-forms are unknown.The recommendations for energy levels are based on a consensus following careful review of the current literature.Although energy levels are selected for de?brillation,it is the transmyocardial current ?ow that achieves de?brilla-
C.D.Deakin et al./Resuscitation81(2010)1293–13041299
tion.Current correlates well with successful de?brillation and cardioversion.144The optimal current for de?brillation using a monophasic waveform is in the range of30–40A.Indirect evidence from measurements during cardioversion for atrial?brillation suggests that the current during de?brillation using biphasic wave-forms is in the range of15–20A.137Future technology may enable de?brillators to discharge according to transthoracic current;a strategy that may lead to greater consistency in shock success. Peak current amplitude,average current and phase duration all need to be studied to determine optimal values and manufacturers are encouraged to explore further this move from energy-based to current-based de?brillation.
First shock
Monophasic de?brillators
There are no new published studies looking at the optimal energy levels for monophasic waveforms since publication of the 2005guidelines.First shock ef?cacy for long duration cardiac arrest using monophasic de?brillation has been reported as54–63%for a200J monophasic truncated exponential(MTE)waveform129,145 and77–91%using a200J monophasic damped sinusoidal(MDS) waveform.128–130,145Because of the lower ef?cacy of this wave-form,the recommended initial energy level for the?rst shock using a monophasic de?brillator is360J.Although higher energy levels risk a greater degree of myocardial injury,the bene?ts of earlier conversion to a perfusing rhythm are paramount.Atrioventricular block is more common with higher monophasic energy levels,but is generally transient and has been shown not to affect survival to hospital discharge.146Only one of27animal studies demon-strated harm caused by attempted de?brillation using high energy shocks.147
Biphasic de?brillators
Relatively few studies have been published in the past5years on which to re?ne the2005guidelines.There is no evidence that one biphasic waveform or device is more effective than another. First shock ef?cacy of the BTE waveform using150–200J has been reported as86–98%.128,129,145,148,149First shock ef?cacy of the RLB waveform using120J is up to85%(data not published in the paper but supplied by personnel communication).130First shock ef?cacy of a new pulsed biphasic waveform at130J showed a?rst shock success rate of90%.126Two studies have suggested equivalence with lower and higher starting energy biphasic de?brillation.150,151 Although human studies have not shown harm(raised biomarkers, ECG changes,ejection fraction)from any biphasic waveform up to 360J,150,152several animal studies have suggested the potential for harm with higher energy levels.153–156
The initial biphasic shock should be no lower than120J for RLB waveforms and150J for BTE waveforms.Ideally,the initial biphasic shock energy should be at least150J for all waveforms.
Manufacturers should display the effective waveform dose range on the face of the biphasic de?brillator;older monophasic de?brillators should also be marked clearly with the appropriate dose range.If the rescuer is unaware of the recommended energy settings of the de?brillator,use the highest setting for all shocks.
Second and subsequent shocks
The2005guidelines recommended either a?xed or escalating energy strategy for de?brillation.Subsequent to these recommen-dations,several studies have demonstrated that although an esca-lating strategy reduces the number of shocks required to restore an organised rhythm compared with?xed-dose biphasic de?b-rillation,and may be needed for successful de?brillation,157,158 rates of ROSC or survival to hospital discharge are not signi?-cantly different between strategies.150,151Conversely,a?xed-dose biphasic protocol demonstrated high cardioversion rates(>90%) with a three-shock?xed dose protocol but the small number of cases did not exclude a signi?cant lower ROSC rate for recurrent VF.159Several in-hospital studies using an escalating shock energy strategy have demonstrated improvement in cardioversion rates (compared with?xed dose protocols)in non-arrest rhythms with the same level of energy selected for both biphasic and monophasic waveforms.135,137,160–163
Monophasic de?brillators
Because the initial shock has been unsuccessful at360J,second and subsequent shocks should all be delivered at360J.
Biphasic de?brillators
There is no evidence to support either a?xed or escalating energy protocol.Both strategies are acceptable;however,if the?rst shock is not successful and the de?brillator is capable of delivering shocks of higher energy it is reasonable to increase the energy for subsequent shocks.
Recurrent ventricular?brillation
If a shockable rhythm recurs after successful de?brillation with ROSC,give the next shock with the energy level that had previously been successful.
Other related de?brillation topics
De?brillation of children
Cardiac arrest is less common in https://www.360docs.net/doc/08620125.html,mon causes of VF in children include trauma,congenital heart disease,long QT inter-val,drug overdose and hypothermia.164–166Ventricular?brillation is relatively rare compared with adult cardiac arrest,occurring in7-15%of paediatric and adolescent arrests.166–171Rapid de?brillation of these patients may improve outcome.171,172
The optimal energy level,waveform and shock sequence is unknown but as with adults,biphasic shocks appear to be at least as effective as,and less harmful than,monophasic shocks.173–175The upper limit for safe de?brillation is unknown,but doses in excess of the previously recommended maximum of4J kg?1(as high as 9J kg?1)have de?brillated children effectively without signi?cant adverse effects.38,176,177
The recommended energy levels for manual monophasic de?b-rillation are4J kg?1for the initial shock and subsequent shocks. The same energy levels are recommended for manual biphasic de?brillation.178As with adults,if a shockable rhythm recurs,use the energy level for de?brillation that had previously been success-ful.
For de?brillation of children above the age of8years,an AED with standard electrodes is used and standard energy set-tings accepted.For de?brillation of children between1and8 years,special paediatric electrodes and energy attenuators are recommended;these reduce the delivered energy to a level that approaches that of the energy recommended for manual de?brilla-tors.When these electrodes are not available,an AED with standard electrodes should be used.For de?brillation of children below1 year of age,an AED,is not recommended;however,there are a few case reports describing the use of AEDs in children aged less than 1year.179,180The incidence of shockable rhythms in infants is very low except when there is cardiac disease167,181,182;in these rare cases,if an AED is the only de?brillator available,its use should be considered(preferably with dose attenuator).
1300 C.D.Deakin et al./Resuscitation81(2010)1293–1304
Cardioversion
If electrical cardioversion is used to convert atrial or ventric-ular tachyarrhythmias,the shock must be synchronised to occur with the R wave of the electrocardiogram rather than with the T wave:VF can be induced if a shock is delivered during the relative refractory portion of the cardiac cycle.183Synchronisation can be dif?cult in VT because of the wide-complex and variable forms of ventricular arrhythmia.Inspect the synchronisation marker care-fully for consistent recognition of the R wave.If needed,choose another lead and/or adjust the amplitude.If synchronisation fails, give unsynchronised shocks to the unstable patient in VT to avoid prolonged delay in restoring sinus rhythm.Ventricular?brillation or pulseless VT requires unsynchronised shocks.Conscious patients must be anaesthetised or sedated before attempting synchronised cardioversion.
Atrial?brillation
Optimal electrode position has been discussed previously,but anterolateral and antero-posterior are both acceptable positions. Biphasic waveforms are more effective than monophasic wave-forms for cardioversion of AF135–138;and cause less severe skin burns.184When available,a biphasic de?brillator should be used in preference to a monophasic de?brillator.Differences in biphasic waveforms themselves have not been established.
Monophasic waveforms
A study of electrical cardioversion for atrial?brillation indicated that360J monophasic damped sinusoidal(MDS)shocks were more effective than100or200J MDS shocks.185Although a?rst shock of360J reduces overall energy requirements for cardioversion,185 360J may cause greater myocardial damage and skin burns than occurs with lower monophasic energy levels and this must be taken into https://www.360docs.net/doc/08620125.html,mence synchronised cardioversion of atrial ?brillation using an initial energy level of200J,increasing in a stepwise manner as necessary.
Biphasic waveforms
More data are needed before speci?c recommendations can be made for optimal biphasic energy https://www.360docs.net/doc/08620125.html,mencing at high energy levels has not shown to result in more successful cardiover-sion rates compared to lower energy levels.135,186–191An initial synchronised shock of120–150J,escalating if necessary is a rea-sonable strategy based on current data.
Atrial?utter and paroxysmal supraventricular tachycardia Atrial?utter and paroxysmal SVT generally require less energy than atrial?brillation for cardioversion.190Give an initial shock of100J monophasic or70–120J biphasic.Give subsequent shocks using stepwise increases in energy.144
Ventricular tachycardia
The energy required for cardioversion of VT depends on the morphological characteristics and rate of the arrhythmia.192Ven-tricular tachycardia with a pulse responds well to cardioversion using initial monophasic energies https://www.360docs.net/doc/08620125.html,e biphasic energy lev-els of120–150J for the initial shock.Consider stepwise increases if the?rst shock fails to achieve sinus rhythm.192Pacing
Consider pacing in patients with symptomatic bradycardia refractory to anti-cholinergic drugs or other second line ther-apy(see Section4).113Immediate pacing is indicated especially when the block is at or below the His-Purkinje level.If transtho-racic pacing is ineffective,consider transvenous pacing.Whenever a diagnosis of asystole is made,check the ECG carefully for the presence of P waves because this will likely respond to cardiac pacing.The use of epicardial wires to pace the myocardium fol-lowing cardiac surgery is effective and discussed elsewhere.Do not attempt pacing for asystole unless P waves are present;it does not increase short or long-term survival in-or out-of-hospital.193–201 For haemodynamically unstable,conscious patients with brad-yarrhythmias,percussion pacing as a bridge to electrical pacing may be attempted,although its effectiveness has not been estab-lished.
Implantable cardioverter de?brillators
Implantable cardioverter de?brillators(ICDs)are becoming increasingly common as the devices are implanted more frequently as the population ages.They are implanted because a patient is con-sidered to be at risk from,or has had,a life-threatening shockable arrhythmia and are usually embedded under the pectoral mus-cle below the left clavicle(in a similar position to pacemakers, from which they cannot be immediately distinguished).On sens-ing a shockable rhythm,an ICD will discharge approximately40J through an internal pacing wire embedded in the right ventricle. On detecting VF/VT,ICD devices will discharge no more than eight times,but may reset if they detect a new period of VF/VT.Patients with fractured ICD leads may suffer repeated internal de?brillation as the electrical noise is mistaken for a shockable rhythm;in these circumstances,the patient is likely to be conscious,with the ECG showing a relatively normal rate.A magnet placed over the ICD will disable the de?brillation function in these circumstances.
Discharge of an ICD may cause pectoral muscle contraction in the patient,and shocks to the rescuer have been documented.202In view of the low energy levels discharged by ICDs,it is unlikely that any harm will come to the rescuer,but the wearing of gloves and minimising contact with the patient whilst the device is discharging is prudent.Cardioverter and pacing function should always be re-evaluated following external de?brillation,both to check the device itself and to check pacing/de?brillation thresholds of the device leads.
Pacemaker spikes generated by devices programmed to unipo-lar pacing may confuse AED software and emergency personnel, and may prevent the detection of VF.203The diagnostic algorithms of modern AEDs are insensitive to such spikes.
References
1.Deakin CD,Nolan JP.European Resuscitation Council guidelines for
resuscitation2005.Section3.Electrical therapies:automated external de?b-rillators,de?brillation,cardioversion and pacing.Resuscitation2005;67(Suppl.
1):S25–37.
2.Proceedings of the2005International Consensus on Cardiopulmonary
Resuscitation and Emergency Cardiovascular Care Science with Treatment Rec-ommendations.Resuscitation2005;67:157–341.
https://www.360docs.net/doc/08620125.html,rsen MP,Eisenberg MS,Cummins RO,Hallstrom AP.Predicting survival
from out-of-hospital cardiac arrest:a graphic model.Ann Emerg Med 1993;22:1652–8.
4.Valenzuela TD,Roe DJ,Cretin S,Spaite DW,Larsen MP.Estimating effectiveness
of cardiac arrest interventions:a logistic regression survival model.Circulation 1997;96:3308–13.
5.Waalewijn RA,de Vos R,Tijssen JG,Koster RW.Survival models for out-of-
hospital cardiopulmonary resuscitation from the perspectives of the bystander, the?rst responder,and the paramedic.Resuscitation2001;51:113–22.
C.D.Deakin et al./Resuscitation81(2010)1293–13041301
6.Weisfeldt ML,Sitlani CM,Ornato JP,et al.Survival after application of auto-
matic external de?brillators before arrival of the emergency medical system: evaluation in the resuscitation outcomes consortium population of21million.
J Am Coll Cardiol2010;55:1713–20.
7.Myerburg RJ,Fenster J,Velez M,et al.Impact of community-wide police
car deployment of automated external de?brillators on survival from out-of-hospital cardiac arrest.Circulation2002;106:1058–64.
8.Capucci A,Aschieri D,Piepoli MF,Bardy GH,Iconomu E,Arvedi M.Tripling
survival from sudden cardiac arrest via early de?brillation without traditional education in cardiopulmonary resuscitation.Circulation2002;106:1065–70.
9.van Alem AP,Vrenken RH,de Vos R,Tijssen JG,Koster https://www.360docs.net/doc/08620125.html,e of auto-
mated external de?brillator by?rst responders in out of hospital cardiac arrest: prospective controlled trial.BMJ2003;327:1312.
10.Valenzuela TD,Bjerke HS,Clark LL,et al.Rapid de?brillation by nontraditional
responders:the Casino Project.Acad Emerg Med1998;5:414–5.
11.Spearpoint KG,Gruber PC,Brett SJ.Impact of the Immediate Life Support course
on the incidence and outcome of in-hospital cardiac arrest calls:an observa-tional study over6years.Resuscitation2009;80:638–43.
12.Waalewijn RA,Tijssen JG,Koster RW.Bystander initiated actions in out-
of-hospital cardiopulmonary resuscitation:results from the Amsterdam Resuscitation Study(ARREST).Resuscitation2001;50:273–9.
13.Swor RA,Jackson RE,Cynar M,et al.Bystander CPR,ventricular?brillation,and
survival in witnessed,unmonitored out-of-hospital cardiac arrest.Ann Emerg Med1995;25:780–4.
14.Holmberg M,Holmberg S,Herlitz J.Effect of bystander cardiopulmonary resus-
citation in out-of-hospital cardiac arrest patients in Sweden.Resuscitation 2000;47:59–70.
15.Vaillancourt C,Verma A,Trickett J,et al.Evaluating the effectiveness of
dispatch-assisted cardiopulmonary resuscitation instructions.Acad Emerg Med2007;14:877–83.
16.O’Neill JF,Deakin CD.Evaluation of telephone CPR advice for adult cardiac arrest
patients.Resuscitation2007;74:63–7.
17.Yang CW,Wang HC,Chiang WC,et al.Interactive video instruction improves
the quality of dispatcher-assisted chest compression-only cardiopulmonary resuscitation in simulated cardiac arrests.Crit Care Med2009;37:490–5. 18.Yang CW,Wang HC,Chiang WC,et al.Impact of adding video communication
to dispatch instructions on the quality of rescue breathing in simulated cardiac arrests—a randomized controlled study.Resuscitation2008;78:327–32.
19.Koster RW,Baubin MA,Caballero A,et al.European Resuscitation Council
Guidelines for Resuscitation2010.Section2.Adult basic life support and use of automated external de?brillators.Resuscitation2010;81:1277–92.
20.Berdowski J,Schulten RJ,Tijssen JG,van Alem AP,Koster RW.Delaying a shock
after takeover from the automated external de?brillator by paramedics is asso-ciated with decreased survival.Resuscitation2010;81:287–92.
21.Zafari AM,Zarter SK,Heggen V,et al.A program encouraging early de?bril-
lation results in improved in-hospital resuscitation ef?cacy.J Am Coll Cardiol 2004;44:846–52.
22.Destro A,Marzaloni M,Sermasi S,Rossi F.Automatic external de?brillators in
the hospital as well?Resuscitation1996;31:39–43.
23.Forcina MS,Farhat AY,O’Neil WW,Haines DE.Cardiac arrest survival after
implementation of automated external de?brillator technology in the in-hospital setting.Crit Care Med2009;37:1229–36.
24.Domanovits H,Meron G,Sterz F,et al.Successful automatic external de?brilla-
tor operation by people trained only in basic life support in a simulated cardiac arrest situation.Resuscitation1998;39:47–50.
25.Cusnir H,Tongia R,Sheka KP,et al.In hospital cardiac arrest:a role for automatic
de?brillation.Resuscitation2004;63:183–8.
26.Chan PS,Krumholz HM,Nichol G,Nallamothu BK.Delayed time to de?brillation
after in-hospital cardiac arrest.N Engl J Med2008;358:9–17.
27.Cummins RO,Eisenberg MS,Litwin PE,Graves JR,Hearne TR,Hallstrom AP.
Automatic external de?brillators used by emergency medical technicians:a controlled clinical trial.JAMA1987;257:1605–10.
28.Stults KR,Brown DD,Kerber RE.Ef?cacy of an automated external de?brillator
in the management of out-of-hospital cardiac arrest:validation of the diagnos-tic algorithm and initial clinical experience in a rural environment.Circulation 1986;73:701–9.
29.Kramer-Johansen J,Edelson DP,Abella BS,Becker LB,Wik L,Steen PA.Pauses
in chest compression and inappropriate shocks:a comparison of manual and semi-automatic de?brillation attempts.Resuscitation2007;73:212–20.
30.Pytte M,Pedersen TE,Ottem J,Rokvam AS,Sunde https://www.360docs.net/doc/08620125.html,parison of hands-off
time during CPR with manual and semi-automatic de?brillation in a manikin model.Resuscitation2007;73:131–6.
31.Edelson DP,Abella BS,Kramer-Johansen J,et al.Effects of compression depth
and pre-shock pauses predict de?brillation failure during cardiac arrest.Resus-citation2006;71:137–45.
32.Eftestol T,Sunde K,Steen PA.Effects of interrupting precordial compressions
on the calculated probability of de?brillation success during out-of-hospital cardiac arrest.Circulation2002;105:2270–3.
33.Yu T,Weil MH,Tang W,et al.Adverse outcomes of interrupted precordial
compression during automated de?brillation.Circulation2002;106:368–72.
34.Wik L,Kramer-Johansen J,Myklebust H,et al.Quality of cardiopulmonary
resuscitation during out-of-hospital cardiac arrest.JAMA2005;293:299–304.
35.Abella BS,Alvarado JP,Myklebust H,et al.Quality of cardiopulmonary resusci-
tation during in-hospital cardiac arrest.JAMA2005;293:305–10.
36.Kerber RE,Becker LB,Bourland JD,et al.Automatic external de?brillators for
public access de?brillation:recommendations for specifying and reporting
arrhythmia analysis algorithm performance,incorporating new waveforms, and enhancing safety.A statement for health professionals from the American Heart Association Task Force on Automatic External De?brillation,Subcom-mittee on AED Safety and Ef?cacy.Circulation1997;95:1677–82.
37.Dickey W,Dalzell GW,Anderson JM,Adgey AA.The accuracy of decision-
making of a semi-automatic de?brillator during cardiac arrest.Eur Heart J 1992;13:608–15.
38.Atkinson E,Mikysa B,Conway JA,et al.Speci?city and sensitivity of automated
external de?brillator rhythm analysis in infants and children.Ann Emerg Med 2003;42:185–96.
39.Cecchin F,Jorgenson DB,Berul CI,et al.Is arrhythmia detection by automatic
external de?brillator accurate for children?Sensitivity and speci?city of an automatic external de?brillator algorithm in696pediatric arrhythmias.Circu-lation2001;103:2483–8.
40.van Alem AP,Sanou BT,Koster RW.Interruption of cardiopulmonary resusci-
tation with the use of the automated external de?brillator in out-of-hospital cardiac arrest.Ann Emerg Med2003;42:449–57.
41.Rea TD,Helbock M,Perry S,et al.Increasing use of cardiopulmonary resuscita-
tion during out-of-hospital ventricular?brillation arrest:survival implications of guideline changes.Circulation2006;114:2760–5.
42.Gundersen K,Kvaloy JT,Kramer-Johansen J,Steen PA,Eftestol T.Development
of the probability of return of spontaneous circulation in intervals without chest compressions during out-of-hospital cardiac arrest:an observational study.BMC Med2009;7:6.
43.Lloyd MS,Heeke B,Walter PF,Langberg JJ.Hands-on de?brillation:an analy-
sis of electrical current?ow through rescuers in direct contact with patients during biphasic external de?brillation.Circulation2008;117:2510–4.
https://www.360docs.net/doc/08620125.html,ler PH.Potential?re hazard in de?brillation.JAMA1972;221:192.
45.Hummel III RS,Ornato JP,Weinberg SM,Clarke AM.Spark-generating proper-
ties of electrode gels used during de?brillation.A potential?re hazard.JAMA 1988;260:3021–4.
46.ECRI.De?brillation in oxygen-enriched environments[hazard].Health Devices
1987;16:113–4.
47.Lefever J,Smith A.Risk of?re when using de?brillation in an oxygen enriched
atmosphere.Med Devices Agency Safety Notices1995;3:1–3.
48.Ward ME.Risk of?res when using de?brillators in an oxygen enriched atmo-
sphere.Resuscitation1996;31:173.
49.Theodorou AA,Gutierrez JA,Berg RA.Fire attributable to a de?brillation
attempt in a neonate.Pediatrics2003;112:677–9.
50.Robertshaw H,McAnulty G.Ambient oxygen concentrations during simulated
cardiopulmonary resuscitation.Anaesthesia1998;53:634–7.
51.Cantello E,Davy TE,Koenig KL.The question of removing a ventilation bag
before de?brillation.J Accid Emerg Med1998;15:286.
52.Deakin CD,Paul V,Fall E,Petley GW,Thompson F.Ambient oxygen concentra-
tions resulting from use of the Lund University Cardiopulmonary Assist System (LUCAS)device during simulated cardiopulmonary resuscitation.Resuscitation 2007;74:303–9.
53.Kerber RE,Kouba C,Martins J,et al.Advance prediction of transtho-
racic impedance in human de?brillation and cardioversion:importance of impedance in determining the success of low-energy shocks.Circulation 1984;70:303–8.
54.Kerber RE,Grayzel J,Hoyt R,Marcus M,Kennedy J.Transthoracic resistance in
human de?brillation.In?uence of body weight,chest size,serial shocks,paddle size and paddle contact pressure.Circulation1981;63:676–82.
55.Sado DM,Deakin CD,Petley GW,Clewlow https://www.360docs.net/doc/08620125.html,parison of the effects of
removal of chest hair with not doing so before external de?brillation on transthoracic impedance.Am J Cardiol2004;93:98–100.
56.Walsh SJ,McCarty D,McClelland AJ,et al.Impedance compensated biphasic
waveforms for transthoracic cardioversion of atrial?brillation:a multi-centre comparison of antero-apical and antero-posterior pad positions.Eur Heart J 2005;26:1298–302.
57.Deakin CD,Sado DM,Petley GW,Clewlow F.Differential contribution of skin
impedance and thoracic volume to transthoracic impedance during external de?brillation.Resuscitation2004;60:171–4.
58.Deakin C,Sado D,Petley G,Clewlow F.Determining the optimal paddle force
for external de?brillation.Am J Cardiol2002;90:812–3.
59.Manegold JC,Israel CW,Ehrlich JR,et al.External cardioversion of atrial?b-
rillation in patients with implanted pacemaker or cardioverter-de?brillator systems:a randomized comparison of monophasic and biphasic shock energy application.Eur Heart J2007;28:1731–8.
60.Alferness CA.Pacemaker damage due to external countershock in patients
with implanted cardiac pacemakers.Pacing Clin Electrophysiol1982;5: 457–8.
61.Panacek EA,Munger MA,Rutherford WF,Gardner SF.Report of nitropatch
explosions complicating de?brillation.Am J Emerg Med1992;10:128–9.
62.Wrenn K.The hazards of de?brillation through nitroglycerin patches.Ann
Emerg Med1990;19:1327–8.
63.Pagan-Carlo LA,Spencer KT,Robertson CE,Dengler A,Birkett C,Kerber
RE.Transthoracic de?brillation:importance of avoiding electrode placement directly on the female breast.J Am Coll Cardiol1996;27:449–52.
64.Deakin CD,Sado DM,Petley GW,Clewlow F.Is the orientation of the api-
cal de?brillation paddle of importance during manual external de?brillation?
Resuscitation2003;56:15–8.
65.Kirchhof P,Eckardt L,Loh P,et al.Anterior-posterior versus anterior-lateral
electrode positions for external cardioversion of atrial?brillation:a ran-domised https://www.360docs.net/doc/08620125.html,ncet2002;360:1275–9.
1302 C.D.Deakin et al./Resuscitation81(2010)1293–1304
66.Botto GL,Politi A,Bonini W,Broffoni T,Bonatti R.External cardioversion of atrial
?brillation:role of paddle position on technical ef?cacy and energy require-ments.Heart1999;82:726–30.
67.Alp NJ,Rahman S,Bell JA,Shahi M.Randomised comparison of antero-lateral
versus antero-posterior paddle positions for DC cardioversion of persistent atrial?brillation.Int J Cardiol2000;75:211–6.
68.Mathew TP,Moore A,McIntyre M,et al.Randomised comparison of electrode
positions for cardioversion of atrial?brillation.Heart1999;81:576–9.
69.Deakin CD,McLaren RM,Petley GW,Clewlow F,Dalrymple-Hay MJ.Effects
of positive end-expiratory pressure on transthoracic impedance—implications for de?brillation.Resuscitation1998;37:9–12.
70.American National Standard:automatic external de?brillators and remote
controlled de?brillators(DF39).Arlington,Virgina:Association for the Advancement of Medical Instrumentation;1993.
71.Deakin CD,McLaren RM,Petley GW,Clewlow F,Dalrymple-Hay MJ.A com-
parison of transthoracic impedance using standard de?brillation paddles and self-adhesive de?brillation pads.Resuscitation1998;39:43–6.
72.Stults KR,Brown DD,Cooley F,Kerber RE.Self-adhesive monitor/de?brillation
pads improve prehospital de?brillation success.Ann Emerg Med 1987;16:872–7.
73.Bojar RM,Payne DD,Rastegar H,Diehl JT,Cleveland https://www.360docs.net/doc/08620125.html,e of self-adhesive
external de?brillator pads for complex cardiac surgical procedures.Ann Thorac Surg1988;46:587–8.
74.Bradbury N,Hyde D,Nolan J.Reliability of ECG monitoring with a gel
pad/paddle combination after de?brillation.Resuscitation2000;44:203–6. 75.Brown J,Rogers J,Soar J.Cardiac arrest during surgery and ventilation
in the prone position:a case report and systematic review.Resuscitation 2001;50:233–8.
76.Perkins GD,Davies RP,Soar J,Thickett DR.The impact of manual de?brillation
technique on no-?ow time during simulated cardiopulmonary resuscitation.
Resuscitation2007;73:109–14.
77.Wilson RF,Sirna S,White CW,Kerber RE.De?brillation of high-risk patients
during coronary angiography using self-adhesive,preapplied electrode pads.
Am J Cardiol1987;60:380–2.
78.Kerber RE,Martins JB,Kelly KJ,et al.Self-adhesive preapplied electrode pads
for de?brillation and cardioversion.J Am Coll Cardiol1984;3:815–20.
79.Kerber RE,Martins JB,Ferguson DW,et al.Experimental evaluation and initial
clinical application of new self-adhesive de?brillation electrodes.Int J Cardiol 1985;8:57–66.
80.Perkins GD,Roberts C,Gao F.Delays in de?brillation:in?uence of different
monitoring techniques.Br J Anaesth2002;89:405–8.
81.Chamberlain D.Gel pads should not be used for monitoring ECG after de?bril-
lation.Resuscitation2000;43:159–60.
82.Callaway CW,Sherman LD,Mosesso Jr VN,Dietrich TJ,Holt E,Clarkson MC.
Scaling exponent predicts de?brillation success for out-of-hospital ventricular ?brillation cardiac arrest.Circulation2001;103:1656–61.
83.Eftestol T,Sunde K,Aase SO,Husoy JH,Steen PA.Predicting outcome of
de?brillation by spectral characterization and nonparametric classi?cation of ventricular?brillation in patients with out-of-hospital cardiac arrest.Circula-tion2000;102:1523–9.
84.Eftestol T,Wik L,Sunde K,Steen PA.Effects of cardiopulmonary resuscitation
on predictors of ventricular?brillation de?brillation success during out-of-hospital cardiac arrest.Circulation2004;110:10–5.
85.Weaver WD,Cobb LA,Dennis D,Ray R,Hallstrom AP,Copass MK.Amplitude of
ventricular?brillation waveform and outcome after cardiac arrest.Ann Intern Med1985;102:53–5.
86.Brown CG,Dzwonczyk R.Signal analysis of the human electrocardiogram dur-
ing ventricular?brillation:frequency and amplitude parameters as predictors of successful countershock.Ann Emerg Med1996;27:184–8.
87.Callaham M,Braun O,Valentine W,Clark DM,Zegans C.Prehospital car-
diac arrest treated by urban?rst-responders:pro?le of patient response and prediction of outcome by ventricular?brillation waveform.Ann Emerg Med 1993;22:1664–77.
88.Strohmenger HU,Lindner KH,Brown CG.Analysis of the ventricular?brillation
ECG signal amplitude and frequency parameters as predictors of countershock success in humans.Chest1997;111:584–9.
89.Strohmenger HU,Eftestol T,Sunde K,et al.The predictive value of ventricu-
lar?brillation electrocardiogram signal frequency and amplitude variables in patients with out-of-hospital cardiac arrest.Anesth Analg2001;93:1428–33.
90.Podbregar M,Kovacic M,Podbregar-Mars A,Brezocnik M.Predicting de?brilla-
tion success by‘genetic’programming in patients with out-of-hospital cardiac arrest.Resuscitation2003;57:153–9.
91.Menegazzi JJ,Callaway CW,Sherman LD,et al.Ventricular?brillation scaling
exponent can guide timing of de?brillation and other therapies.Circulation 2004;109:926–31.
92.Povoas HP,Weil MH,Tang W,Bisera J,Klouche K,Barbatsis A.Predicting
the success of de?brillation by electrocardiographic analysis.Resuscitation 2002;53:77–82.
93.Noc M,Weil MH,Tang W,Sun S,Pernat A,Bisera J.Electrocardiographic pre-
diction of the success of cardiac resuscitation.Crit Care Med1999;27:708–14.
94.Strohmenger HU,Lindner KH,Keller A,Lindner IM,Pfenninger EG.Spectral
analysis of ventricular?brillation and closed-chest cardiopulmonary resusci-tation.Resuscitation1996;33:155–61.
95.Noc M,Weil MH,Gazmuri RJ,Sun S,Biscera J,Tang W.Ventricular?brillation
voltage as a monitor of the effectiveness of cardiopulmonary resuscitation.J Lab Clin Med1994;124:421–6.
96.Lightfoot CB,Nremt P,Callaway CW,et al.Dynamic nature of electrocar-
diographic waveform predicts rescue shock outcome in porcine ventricular ?brillation.Ann Emerg Med2003;42:230–41.
97.Marn-Pernat A,Weil MH,Tang W,Pernat A,Bisera J.Optimizing timing of
ventricular de?brillation.Crit Care Med2001;29:2360–5.
98.Hamprecht FA,Achleitner U,Krismer AC,et al.Fibrillation power,an alternative
method of ECG spectral analysis for prediction of countershock success in a porcine model of ventricular?brillation.Resuscitation2001;50:287–96.
99.Amann A,Achleitner U,Antretter H,et al.Analysing ventricular?brilla-
tion ECG-signals and predicting de?brillation success during cardiopulmonary resuscitation employing N(alpha)-histograms.Resuscitation2001;50:77–85. 100.Brown CG,Grif?th RF,Van Ligten P,et al.Median frequency—a new parameter for predicting de?brillation success rate.Ann Emerg Med1991;20:787–9. 101.Amann A,Rheinberger K,Achleitner U,et al.The prediction of de?brillation outcome using a new combination of mean frequency and amplitude in porcine models of cardiac arrest.Anesth Analg2002;95:716–22,table of contents. 102.Cobb LA,Fahrenbruch CE,Walsh TR,et al.In?uence of cardiopulmonary resus-citation prior to de?brillation in patients with out-of-hospital ventricular ?brillation.JAMA1999;281:1182–8.
103.Wik L,Hansen TB,Fylling F,et al.Delaying de?brillation to give basic cardiopul-monary resuscitation to patients with out-of-hospital ventricular?brillation:
a randomized trial.JAMA2003;289:1389–95.
104.Berg RA,Hilwig RW,Kern KB,Ewy GA.Precountershock cardiopul-monary resuscitation improves ventricular?brillation median frequency and myocardial readiness for successful de?brillation from prolonged ventric-ular?brillation:a randomized,controlled swine study.Ann Emerg Med 2002;40:563–70.
105.Berg RA,Hilwig RW,Ewy GA,Kern KB.Precountershock cardiopulmonary resuscitation improves initial response to de?brillation from prolonged ven-tricular?brillation:a randomized,controlled swine study.Crit Care Med 2004;32:1352–7.
106.Kolarova J,Ayoub IM,Yi Z,Gazmuri RJ.Optimal timing for electrical de?b-rillation after prolonged untreated ventricular?brillation.Crit Care Med 2003;31:2022–8.
107.Indik JH,Hilwig RW,Zuercher M,Kern KB,Berg MD,Berg RA.Preshock cardiopulmonary resuscitation worsens outcome from circulatory phase ven-tricular?brillation with acute coronary artery obstruction in swine.Circ Arrhythm Electrophysiol2009;2:179–84.
108.Baker PW,Conway J,Cotton C,et al.De?brillation or cardiopulmonary resuscitation?rst for patients with out-of-hospital cardiac arrests found by paramedics to be in ventricular?brillation?A randomised control trial.Resus-citation2008;79:424–31.
109.Jacobs IG,Finn JC,Oxer HF,Jelinek GA.CPR before de?brillation in out-of-hospital cardiac arrest:a randomized trial.Emerg Med Aust2005;17:39–45. 110.Hayakawa M,Gando S,Okamoto H,Asai Y,Uegaki S,Makise H.Shortening of cardiopulmonary resuscitation time before the de?brillation worsens the outcome in out-of-hospital VF patients.Am J Emerg Med2009;27:470–4. 111.Bradley SM,Gabriel EE,Aufderheide TP,et al.Survival Increases with CPR by Emergency Medical Services before de?brillation of out-of-hospital ventricu-lar?brillation or ventricular tachycardia:observations from the Resuscitation Outcomes Consortium.Resuscitation2010;81:155–62.
112.Christenson J,Andrusiek D,Everson-Stewart S,et al.Chest compression fraction determines survival in patients with out-of-hospital ventricular?brillation.
Circulation2009;120:1241–7.
113.Deakin CD,Nolan JP,Soar J,et al.European Resuscitation Council Guidelines for Resuscitation2010.Section4.Adult advanced life support.Resuscitation 2010;81:1305–52.
114.Berg RA,Sanders AB,Kern KB,et al.Adverse hemodynamic effects of interrupting chest compressions for rescue breathing during cardiopul-monary resuscitation for ventricular?brillation cardiac arrest.Circulation 2001;104:2465–70.
115.Kern KB,Hilwig RW,Berg RA,Sanders AB,Ewy GA.Importance of continuous chest compressions during cardiopulmonary resuscitation:improved outcome during a simulated single lay-rescuer scenario.Circulation2002;105:645–9. 116.Valenzuela TD,Kern KB,Clark LL,et al.Interruptions of chest compressions dur-ing emergency medical systems resuscitation.Circulation2005;112:1259–65. 117.Bain AC,Swerdlow CD,Love CJ,et al.Multicenter study of principles-based waveforms for external de?brillation.Ann Emerg Med2001;37:5–12.
118.Poole JE,White RD,Kanz KG,et al.Low-energy impedance-compensating biphasic waveforms terminate ventricular?brillation at high rates in victims of out-of-hospital cardiac arrest.LIFE Investigators.J Cardiovasc Electrophysiol 1997;8:1373–85.
119.Schneider T,Martens PR,Paschen H,et al.Multicenter,randomized,controlled trial of150-J biphasic shocks compared with200-to360-J monopha-sic shocks in the resuscitation of out-of-hospital cardiac arrest victims.
Optimized Response to Cardiac Arrest(ORCA)Investigators.Circulation 2000;102:1780–7.
120.Rea TD,Shah S,Kudenchuk PJ,Copass MK,Cobb LA.Automated external de?brillators:to what extent does the algorithm delay CPR?Ann Emerg Med 2005;46:132–41.
121.Olasveengen TM,Vik E,Kuzovlev A,Sunde K.Effect of implementation of new resuscitation guidelines on quality of cardiopulmonary resuscitation and sur-vival.Resuscitation2009;80:407–11.
122.Bobrow BJ,Clark LL,Ewy GA,et al.Minimally interrupted cardiac resuscita-tion by emergency medical services for out-of-hospital cardiac arrest.JAMA 2008;299:1158–65.
C.D.Deakin et al./Resuscitation81(2010)1293–13041303
123.Steinmetz J,Barnung S,Nielsen SL,Risom M,Rasmussen LS.Improved survival after an out-of-hospital cardiac arrest using new guidelines.Acta Anaesthesiol Scand2008;52:908–13.
124.Jost D,Degrange H,Verret C,et al.DEFI2005:a randomized controlled trial of the effect of automated external de?brillator cardiopulmonary resusci-tation protocol on outcome from out-of-hospital cardiac arrest.Circulation 2010;121:1614–22.
125.Soar J,Perkins GD,Abbas G,et al.European Resuscitation Council Guidelines for Resuscitation2010.Section8.Cardiac arrest in special circumstances: electrolyte abnormalities,poisoning,drowning,accidental hypothermia, hyperthermia,asthma,anaphylaxis,cardiac surgery,trauma,pregnancy,elec-trocution.Resuscitation2010;81:1400–33.
126.Didon JP,Fontaine G,White RD,Jekova I,Schmid JJ,Cansell A.Clinical experi-ence with a low-energy pulsed biphasic waveform in out-of-hospital cardiac arrest.Resuscitation2008;76:350–3.
127.Li Y,Wang H,Cho JH,et https://www.360docs.net/doc/08620125.html,parison of ef?cacy of pulsed biphasic waveform and rectilinear biphasic waveform in a short ventricular?brillation pig model.
Resuscitation2009;80:1047–51.
128.van Alem AP,Chapman FW,Lank P,Hart AA,Koster RW.A prospective, randomised and blinded comparison of?rst shock success of monopha-sic and biphasic waveforms in out-of-hospital cardiac arrest.Resuscitation 2003;58:17–24.
129.Carpenter J,Rea TD,Murray JA,Kudenchuk PJ,Eisenberg MS.De?brillation waveform and post-shock rhythm in out-of-hospital ventricular?brillation cardiac arrest.Resuscitation2003;59:189–96.
130.Morrison LJ,Dorian P,Long J,et al.Out-of-hospital cardiac arrest rectilinear biphasic to monophasic damped sine de?brillation waveforms with advanced life support intervention trial(ORBIT).Resuscitation2005;66:149–57.
131.Gliner BE,White RD.Electrocardiographic evaluation of de?brillation shocks delivered to out-of-hospital sudden cardiac arrest patients.Resuscitation 1999;41:133–44.
132.Freeman K,Hendey GW,Shalit M,Stroh G.Biphasic de?brillation does not improve outcomes compared to monophasic de?brillation in out-of-hospital cardiac arrest.Prehosp Emerg Care2008;12:152–6.
133.Hess EP,Atkinson EJ,White RD.Increased prevalence of sustained return of spontaneous circulation following transition to biphasic waveform de?brilla-tion.Resuscitation2008;77:39–45.
134.Kudenchuk PJ,Cobb LA,Copass MK,Olsufka M,Maynard C,Nichol G.
Transthoracic incremental monophasic versus biphasic de?brillation by emer-gency responders(TIMBER):a randomized comparison of monophasic with biphasic waveform ascending energy de?brillation for the resuscitation of out-of-hospital cardiac arrest due to ventricular?brillation.Circulation 2006;114:2010–8.
135.Mittal S,Ayati S,Stein KM,et al.Transthoracic cardioversion of atrial?brilla-tion:comparison of rectilinear biphasic versus damped sine wave monophasic shocks.Circulation2000;101:1282–7.
136.Page RL,Kerber RE,Russell JK,et al.Biphasic versus monophasic shock waveform for conversion of atrial?brillation:the results of an inter-national randomized,double-blind multicenter trial.J Am Coll Cardiol 2002;39:1956–63.
137.Koster RW,Dorian P,Chapman FW,Schmitt PW,O’Grady SG,Walker RG.A randomized trial comparing monophasic and biphasic waveform shocks for external cardioversion of atrial?brillation.Am Heart J2004;147:e20.
138.Ambler JJ,Deakin CD.A randomized controlled trial of ef?cacy and ST change following use of the Welch-Allyn MRL PIC biphasic waveform versus damped sine monophasic waveform for external DC cardioversion.Resuscita-tion2006;71:146–51.
139.Pagan-Carlo LA,Allan JJ,Spencer KT,Birkett CL,Myers R,Kerber RE.Encircling overlapping multipulse shock waveforms for transthoracic de?brillation.J Am Coll Cardiol1998;32:2065–71.
140.Zhang Y,Ramabadran RS,Boddicker KA,et al.Triphasic waveforms are superior to biphasic waveforms for transthoracic de?brillation:experimental studies.J Am Coll Cardiol2003;42:568–75.
141.Zhang Y,Rhee B,Davies LR,et al.Quadriphasic waveforms are superior to triphasic waveforms for transthoracic de?brillation in a cardiac arrest swine model with high impedance.Resuscitation2006;68:251–8.
142.Kerber RE.External de?brillation:new technologies.Ann Emerg Med 1984;13:794–7.
143.Joglar JA,Kessler DJ,Welch PJ,et al.Effects of repeated electrical de?brillations on cardiac troponin I levels.Am J Cardiol1999;83:270–2.A6.
144.Kerber RE,Martins JB,Kienzle MG,et al.Energy,current,and success in de?bril-lation and cardioversion:clinical studies using an automated impedance-based method of energy adjustment.Circulation1988;77:1038–46.
145.Martens PR,Russell JK,Wolcke B,et al.Optimal Response to Cardiac Arrest study:de?brillation waveform effects.Resuscitation2001;49:233–43.
146.Weaver WD,Cobb LA,Copass MK,Hallstrom AP.Ventricular de?brillation:a comparative trial using175-J and320-J shocks.N Engl J Med1982;307:1101–6. 147.Tang W,Weil MH,Sun S,et al.The effects of biphasic and conventional monophasic de?brillation on postresuscitation myocardial function.J Am Coll Cardiol1999;34:815–22.
148.Gliner BE,Jorgenson DB,Poole JE,et al.Treatment of out-of-hospital cardiac arrest with a low-energy impedance-compensating biphasic waveform auto-matic external de?brillator.The LIFE Investigators.Biomed Instrum Technol 1998;32:631–44.
149.White RD,Blackwell TH,Russell JK,Snyder DE,Jorgenson DB.Transthoracic impedance does not affect de?brillation,resuscitation or survival in patients
with out-of-hospital cardiac arrest treated with a non-escalating biphasic waveform de?brillator.Resuscitation2005;64:63–9.
150.Stiell IG,Walker RG,Nesbitt LP,et al.BIPHASIC Trial:a randomized comparison of?xed lower versus escalating higher energy levels for de?brillation in out-of-hospital cardiac arrest.Circulation2007;115:1511–7.
151.Walsh SJ,McClelland AJ,Owens CG,et al.Ef?cacy of distinct energy delivery protocols comparing two biphasic de?brillators for cardiac arrest.Am J Cardiol 2004;94:378–80.
152.Higgins SL,Herre JM,Epstein AE,et al.A comparison of biphasic and monopha-sic shocks for external de?brillation.Physio-Control Biphasic Investigators.
Prehosp Emerg Care2000;4:305–13.
153.Berg RA,Samson RA,Berg MD,et al.Better outcome after pediatric de?brillation dosage than adult dosage in a swine model of pediatric ventricular?brillation.
J Am Coll Cardiol2005;45:786–9.
154.Killingsworth CR,Melnick SB,Chapman FW,et al.De?brillation threshold and cardiac responses using an external biphasic de?brillator with pedi-atric and adult adhesive patches in pediatric-sized piglets.Resuscitation 2002;55:177–85.
155.Tang W,Weil MH,Sun S,et al.The effects of biphasic waveform design on post-resuscitation myocardial function.J Am Coll Cardiol2004;43:1228–35. 156.Xie J,Weil MH,Sun S,et al.High-energy de?brillation increases the severity of postresuscitation myocardial dysfunction.Circulation1997;96:683–8.
157.Koster RW,Walker RG,Chapman FW.Recurrent ventricular?brillation during advanced life support care of patients with prehospital cardiac arrest.Resus-citation2008;78:252–7.
158.Walker RG,Koster RW,Sun C,et al.De?brillation probability and impedance change between shocks during resuscitation from out-of-hospital cardiac arrest.Resuscitation2009;80:773–7.
159.Hess EP,Russell JK,Liu PY,White RD.A high peak current150-J?xed-energy de?brillation protocol treats recurrent ventricular?brillation(VF)as effec-tively as initial VF.Resuscitation2008;79:28–33.
160.Deakin CD,Ambler JJ.Post-shock myocardial stunning:a prospective ran-domised double-blind comparison of monophasic and biphasic waveforms.
Resuscitation2006;68:329–33.
161.Khaykin Y,Newman D,Kowalewski M,Korley V,Dorian P.Biphasic versus monophasic cardioversion in shock-resistant atrial?brillation.J Cardiovasc Electrophysiol2003;14:868–72.
162.Kmec https://www.360docs.net/doc/08620125.html,parison the effectiveness of damped sine wave monophasic and rectilinear biphasic shocks in patients with persistent atrial?brillation.Kardi-ologia2006;15:265–78.
163.Kosior DA,Szulec M,Torbicki A,Opolski G,Rabczenko D.A decrease of enlarged left atrium following cardioversion of atrial?brillationpredicts the long-term maintenance of sinus rhythm.Kardiol Pol2005;62:428–37.
164.Kuisma M,Suominen P,Korpela R.Paediatric out-of-hospital cardiac arrests: epidemiology and outcome.Resuscitation1995;30:141–50.
165.Sirbaugh PE,Pepe PE,Shook JE,et al.A prospective,population-based study of the demographics,epidemiology,management,and outcome of out-of-hospital pediatric cardiopulmonary arrest.Ann Emerg Med1999;33:174–
84.
166.Hickey RW,Cohen DM,Strausbaugh S,Dietrich AM.Pediatric patients requiring CPR in the prehospital setting.Ann Emerg Med1995;25:495–501.
167.Atkins DL,Everson-Stewart S,Sears GK,et al.Epidemiology and outcomes from out-of-hospital cardiac arrest in children:the Resuscitation Outcomes Consortium Epistry-Cardiac Arrest.Circulation2009;119:1484–91.
168.Appleton GO,Cummins RO,Larson MP,Graves JR.CPR and the single rescuer: at what age should you“call?rst”rather than“call fast”?Ann Emerg Med 1995;25:492–4.
169.Ronco R,King W,Donley DK,Tilden SJ,Outcome.cost at a children’s hospital fol-lowing resuscitation for out-of-hospital cardiopulmonary arrest.Arch Pediatr Adolesc Med1995;149:210–4.
170.Losek JD,Hennes H,Glaeser P,Hendley G,Nelson DB.Prehospital care of the pulseless,nonbreathing pediatric patient.Am J Emerg Med1987;5:370–4. 171.Mogayzel C,Quan L,Graves JR,Tiedeman D,Fahrenbruch C,Herndon P.Out-of-hospital ventricular?brillation in children and adolescents:causes and outcomes.Ann Emerg Med1995;25:484–91.
172.Safranek DJ,Eisenberg MS,Larsen MP.The epidemiology of cardiac arrest in young adults.Ann Emerg Med1992;21:1102–6.
173.Berg RA,Chapman FW,Berg MD,et al.Attenuated adult biphasic shocks com-pared with weight-based monophasic shocks in a swine model of prolonged pediatric ventricular?brillation.Resuscitation2004;61:189–97.
174.Tang W,Weil MH,Jorgenson D,et al.Fixed-energy biphasic waveform de?b-rillation in a pediatric model of cardiac arrest and resuscitation.Crit Care Med 2002;30:2736–41.
175.Clark CB,Zhang Y,Davies LR,Karlsson G,Kerber RE.Pediatric transthoracic de?brillation:biphasic versus monophasic waveforms in an experimental model.Resuscitation2001;51:159–63.
176.Gurnett CA,Atkins DL.Successful use of a biphasic waveform automated exter-nal de?brillator in a high-risk child.Am J Cardiol2000;86:1051–3.
177.Atkins DL,Jorgenson DB.Attenuated pediatric electrode pads for automated external de?brillator use in children.Resuscitation2005;66:31–7.
178.Gutgesell HP,Tacker WA,Geddes LA,Davis S,Lie JT,McNamara DG.Energy dose for ventricular de?brillation of children.Pediatrics1976;58:898–901. 179.Bar-Cohen Y,Walsh EP,Love BA,Cecchin F.First appropriate use of automated external de?brillator in an infant.Resuscitation2005;67:135–7.
180.Divekar A,Soni R.Successful parental use of an automated external de?brillator for an infant with long-QT syndrome.Pediatrics2006;118:e526–9.
1304 C.D.Deakin et al./Resuscitation81(2010)1293–1304
181.Rodriguez-Nunez A,Lopez-Herce J,Garcia C,Dominguez P,Carrillo A,Bellon JM.Pediatric de?brillation after cardiac arrest:initial response and outcome.
Crit Care2006;10:R113.
182.Samson RA,Nadkarni VM,Meaney PA,Carey SM,Berg MD,Berg RA.Out-comes of in-hospital ventricular?brillation in children.N Engl J Med 2006;354:2328–39.
183.Lown B.Electrical reversion of cardiac arrhythmias.Br Heart J1967;29:469–89. 184.Ambler JJ,Deakin CD.A randomised controlled trial of the effect of biphasic or monophasic waveform on the incidence and severity of cutaneous burns fol-lowing external direct current cardioversion.Resuscitation2006;71:293–300. 185.Joglar JA,Hamdan MH,Ramaswamy K,et al.Initial energy for elective external cardioversion of persistent atrial?brillation.Am J Cardiol2000;86:348–50. 186.Boodhoo L,Mitchell AR,Bordoli G,Lloyd G,Patel N,Sulke N.DC cardioversion of persistent atrial?brillation:a comparison of two protocols.Int J Cardiol 2007;114:16–21.
187.Boos C,Thomas MD,Jones A,Clarke E,Wilbourne G,More RS.Higher energy monophasic DC cardioversion for persistent atrial?brillation:is it time to start at360joules?Ann Noninvasive Electrocardiol2003;8:121–6.
188.Glover BM,Walsh SJ,McCann CJ,et al.Biphasic energy selection for transthoracic cardioversion of atrial?brillation.The BEST AF Trial.Heart 2008;94:884–7.
189.Rashba EJ,Gold MR,Crawford FA,Leman RB,Peters RW,Shorofsky SR.Ef?cacy of transthoracic cardioversion of atrial?brillation using a biphasic,truncated exponential shock waveform at variable initial shock energies.Am J Cardiol 2004;94:1572–4.
190.Pinski SL,Sgarbossa EB,Ching E,Trohman RG.A comparison of50-J ver-sus100-J shocks for direct-current cardioversion of atrial?utter.Am Heart J1999;137:439–42.
191.Alatawi F,Gurevitz O,White R.Prospective,randomized comparison of two biphasic waveforms for the ef?cacy and safety of transthoracic biphasic car-dioversion of atrial?brillation.Heart Rhythm2005;2:382–7.192.Kerber RE,Kienzle MG,Olshansky B,et al.Ventricular tachycardia rate and morphology determine energy and current requirements for transthoracic car-dioversion.Circulation1992;85:158–63.
193.Hedges JR,Syverud SA,Dalsey WC,Feero S,Easter R,Shultz B.Prehospital trial of emergency transcutaneous cardiac pacing.Circulation1987;76:1337–43. 194.Barthell E,Troiano P,Olson D,Stueven HA,Hendley G.Prehospital exter-nal cardiac pacing:a prospective,controlled clinical trial.Ann Emerg Med 1988;17:1221–6.
195.Cummins RO,Graves JR,Larsen MP,et al.Out-of-hospital transcutaneous pac-ing by emergency medical technicians in patients with asystolic cardiac arrest.
N Engl J Med1993;328:1377–82.
196.Ornato JP,Peberdy MA.The mystery of bradyasystole during cardiac arrest.
Ann Emerg Med1996;27:576–87.
197.Niemann JT,Adomian GE,Garner D,Rosborough JP.Endocardial and transcuta-neous cardiac pacing,calcium chloride,and epinephrine in postcountershock asystole and bradycardias.Crit Care Med1985;13:699–704.
198.Quan L,Graves JR,Kinder DR,Horan S,Cummins RO.Transcutaneous cardiac pacing in the treatment of out-of-hospital pediatric cardiac arrests.Ann Emerg Med1992;21:905–9.
199.Dalsey WC,Syverud SA,Hedges JR.Emergency department use of transcuta-neous pacing for cardiac arrests.Crit Care Med1985;13:399–401.
200.Knowlton AA,Falk RH.External cardiac pacing during in-hospital cardiac arrest.
Am J Cardiol1986;57:1295–8.
201.Ornato JP,Carveth WL,Windle JR.Pacemaker insertion for prehospital bradyasystolic cardiac arrest.Ann Emerg Med1984;13:101–3.
202.Stockwell B,Bellis G,Morton G,et al.Electrical injury during“hands on”
de?brillation-A potential risk of internal cardioverter de?brillators?Resusci-tation2009;80:832–4.
203.Monsieurs KG,Conraads VM,Goethals MP,Snoeck JP,Bossaert LL.Semi-automatic external de?brillation and implanted cardiac pacemakers:under-standing the interactions during resuscitation.Resuscitation1995;30:127–31.
构造辅助函数证明微分中值定理及应用
构造辅助函数证明微分中值定理及应用 摘要：构造辅助函数是证明中值命题的一种重要途径。本文给出了几种辅助函数的构造方法：微分方程法，常数K值法，几何直观法，原函数法，行列式法；并且举出具体例子加以说明。 关键字：辅助函数，微分方程，微分中值定理 Constructing auxiliary function to prove differential median theorem and its copplications
Abstract: Constructing auxiliary function is the important method to prove median theorem. This paper gives several ways of constructing auxiliary function:Differential equation, Constant K, Geometry law, Primary function law, Determinant law;and Gives some specific examples to illustrate how to constructing. Key words: Auxiliary function; Differential equation; Differential median theorem 目录 一：引言 (4) 二：数学分析中三个中值定理 (4) 三：五种方法构造辅助函数 (6) 1：几何直观法 (6)
2：行列式法…………………………………………………………………… .第7页 3：原函数法 (8) 4：微分方程法 (10) 5：常数k值法 (13) 四：结论 (15) 参考文献 (15) 致谢 (16) 一:引言 微分中值定理是应用导数的局部性质研究函数在区间上的整体性质的基本工具，在高等数学课程中占有十分重要的地位，是微分学的理论基础，这部分内容理论性强，抽象程度高，所谓中值命题是指涉及函数（包括函数的一阶导数，二阶导数等）定义区间中值一些命
最完整的winhex教程
winhex教程 winhex 数据恢复分类：硬恢复和软恢复。所谓硬恢复就是硬盘出现物理性损伤，比如有盘体坏道、电路板芯片烧毁、盘体异响，等故障，由此所导致的普通用户不容易取出里面数据，那么我们将它修好，同时又保留里面的数据或后来恢复里面的数据，这些都叫数据恢复，只不过这些故障有容易的和困难的之分；所谓软恢复，就是硬盘本身没有物理损伤，而是由于人为或者病毒破坏所造成的数据丢失（比如误格式化，误分区），那么这样的数据恢复就叫软恢复。 这里呢，我们主要介绍软恢复，因为硬恢复还需要购买一些工具设备（比如pc3000,电烙铁，各种芯片、电路板），而且还需要懂一点点电路基础，我们这里所讲到的所有的知识，涉及面广，层次深，既有数据结构原理，为我们手工准确恢复数据提供依据，又有各种数据恢复软件的使用方法及技巧，为我们快速恢复数据提供便利，而且所有软件均为网上下载，不需要我们投资一分钱。 数据恢复的前提：数据不能被二次破坏、覆盖！ 关于数码与码制： 关于二进制、十六进制、八进制它们之间的转换我不想多说，因为他对我们数据恢复来说帮助不大，而且很容易把我们绕晕。如果你感兴趣想多了解一些，可以到百度里面去搜一下，这方面资料已经很多了，就不需要我再多说了。 数据恢复我们主要用十六进制编辑器：Winhex （数据恢复首选软件） 我们先了解一下数据结构： 下面是一个分了三个区的整个硬盘的数据结构
MB R C 盘 EB R D 盘 EB R E 盘 MBR，即主引导记录，位于整个硬盘的0柱面0磁道1扇区，共占用了63个扇区，但实际只使用了1个扇区（512字节）。在总共512字节的主引导记录中，MBR又可分为三部分：第一部分：引导代码，占用了446个字节；第二部分：分区表，占用了64字节；第三部分：55AA，结束标志，占用了两个字节。后面我们要说的用winhex软件来恢复误分区，主要就是恢复第二部分：分区表。 引导代码的作用：就是让硬盘具备可以引导的功能。如果引导代码丢失，分区表还在，那么这个硬盘作为从盘所有分区数据都还在，只是这个硬盘自己不能够用来启动进系统了。如果要恢复引导代码，可以用DOS下的命令：FDISK /MBR；这个命令只是用来恢复引导代码，不会引起分区改变，丢失数据。另外，也可以用工具软件，比如DISKGEN、WINHEX等。 但分区表如果丢失，后果就是整个硬盘一个分区没有，就好象刚买来一个新硬盘没有分过区一样。是很多病毒喜欢破坏的区域。 EBR，也叫做扩展MBR（Extended MBR）。因为主引导记录MBR最多只能描述4个分区项，如果想要在一个硬盘上分多于4个区，就要采用扩展MBR 的办法。 MBR、EBR是分区产生的。 比如MBR和EBR各都占用63个扇区，C盘占用1435329个扇区……那么数据结构如下表： 63 1435329 63 1435329 63 1253889 MBR C盘EBR D盘EBR E盘 扩展分区
硬盘分区表错误建议用Disk Genius来进行修复
硬盘分区表错误建议用Disk Genius来进行修复。是一款小巧的硬盘分区表维护工具，大小只有108KB，可是功能却非常强大。Disk Genius中最重要的一项功能就是重建分区表了。如果你的硬盘分区表被分区调整软件(或病毒)严重破坏，引起硬盘和系统瘫痪，Disk Genius可通过未被破坏的分区引导记录信息重新建立分区表。在菜单的工具栏中选择“重建分区”，Disk Genius即开始搜索并重建分区。Disk Genius将首先搜索0柱面0磁头从2扇区开始的隐含扇区，寻找被病毒挪动过的分区表。接下来搜索每个磁头的第一个扇区。搜索过程可以采用“自动”或“交互”两种方式进行。自动方式保留发现的每一个分区，适用于大多数情况。交互方式对发现的每一个分区都给出提示，由用户选择是否保留。当自动方式重建的分区表不正确时，可以采用交互方式重新搜索，只要能重新找回分区，上面的数据都不会丢失EasyRecovery Professional 一个很强悍的数据恢复软件是威力非常强大的硬盘数据恢复工具。能够帮你恢复丢失的数据以及重建文件系统。EasyRecovery不会向你的原始驱动器写入任何东东，它主要是在内存中重建文件分区表使数据能够安全地传输到其他驱动器中。你可以从被病毒破坏或是已经格式化的硬盘中恢复数据。该软件可以恢复大于8.4GB的硬盘。支持长文件名。被破坏的硬盘中像丢失的引导记 录、BIOS参数数据块；分区表；FAT表；引导区都可以由它来进行恢复。https://www.360docs.net/doc/08620125.html,/soft/11308.htm https://www.360docs.net/doc/08620125.html,/soft/35758.htm这个是他的汉化补丁汉化说明：运行汉化补丁后，请在Properties 中的Language 选项中选择“简体中文”并在出现的对话框中选Yes，然后重新启动程序即可看到中文界面。这个版本解决了部分扫描报告乱码的问题。参考资料：https://www.360docs.net/doc/08620125.html,/question/25599238.html 电脑公司特别版GHOST7.6 或者7.8 中自己带的工具中有一个叫分区修复的或者下载个分区修复大师都可以帮你找会误删的分区前些天电脑当机，拆下主板仔细查看，发现在靠近CPU槽的一个电焊接点熔化脱落，估计问题不大，拿到珠江路花25元请人焊好，换了一个电容修好了，回来后发现显示器又点不亮了，又将机器全部拆散，逐个配件的检查，再仔细查看显卡背面，发现有一个零件（不知是电阻还是电容）从中间断裂，手边正好有一块显卡，换上后显示器正常显示，昨天下班回家机器又不能进操作系统了，怀疑是主硬盘分区表被破坏，用diskgen修复，一切正常，再把前几日拆下的一块80GB的硬盘装上，该硬盘分区表还是坏的，进入XP，打开“我的电脑”，只有一个盘符，双击后系统提示“硬盘未格式化”，用手边可启动光盘进入DOS，运行diskgen，选第二硬盘，一选就报错，提示第一分区错误是否修复，我选了"否"，第二扇区柱面错误是否修复,选"否"，中间的界面上显示的硬盘容量是32GB，80GB只识别32GB，不可想象的现象，这块硬盘中全部都是割舍不下的资料。准备试一下，先用diskgen的重建分区表，不理会DISKGEN工具报错的提示，一切报错及修复都选“否”，只在最后一步，“重建分区表”时选“是”，退出时保存修改。重启进入XP，打开“我的电脑”，看到三个分区，只恢复了两个分别为15GB的分区的数据，分区中的文件正常，第三个分区双击时提示“硬盘未格式化”，40G的数据啊还能再回来吗？再试，问题依然未解决，但发现启动光盘上有个叫DM工具，很久就听说过，但从来未用过，就是它了。写到这,前面写的都可以不管它了，下面是我在连续地高强度的试验了近五个小时后得出的最佳步骤,全部过程5分钟左右昨夜1：30分最后一次执行的恢复步骤：1、光盘启动进入DOS，进入DISKGEN（从网上拉一个），恢复分区表（因对硬盘分区写操作过，所以要恢复第一次写操作前保存的分区表信息），保存退出。2、进入DM，有一大堆英文，看不懂，没关系(其实有没有关系已不重要了)，看到有个叫INSTALL的英文，回车，Install下，其它就不要再做了，注意:不要对任何弹出的“YES”进行确认，退出dm。为什么要用dm，原因是我的80G的硬盘，DISKGEN只能识别32G, 用DM引导区的总柱面信息从3826修正到9729，使DISKGEN能正确识别80G. 3、进入DISKGEN，看到容量已恢复为80G，重建分区,重写引导区，保存，退出。4、进入XP，
C语言常用函数
Ｃ语言的常用库函数 函数1。absread()读磁盘绝对扇区函数 原形：int absread(int drive,int num,int sectnum,void *buf) 功能：从drive指定的驱动器磁盘上，sectnum指定的逻辑扇区号开始读取(通过DOS中断0x25读取)num 个(最多64K个)扇区的内容，储存于buf所指的缓冲区中。 参数：drive=0对应A盘,drive=1对应B盘。 返回值：0:成功；-1:失败。 头文件：dos.h 函数2。abswrite()写磁盘绝对扇区函数 原形：int abswrite(int drive,int nsects,int lsect,void *buffer) drive=0(A驱动器)、1(B驱动器)、 nsects=要写的扇区数(最多64K个); lsect=起始逻辑扇区号; buffer=要写入数据的内存起始地址。 功能：将指定内容写入(调用DOS中断0x26)磁盘上的指定扇区，即使写入的地方是磁盘的逻辑结构、文件、FAT表和目录结构所在的扇区，也照常进行。 返回值：0:成功；-1:失败。 头文件：dos.h 函数3。atof()将字符串转换成浮点数的函数 原形：double atof(const char *s) 功能：把s所指向的字符串转换成double类型。 s格式为:符号数字.数字E符号数字 返回值：字符串的转换值。 头文件：math.h、stdlib.h 函数4。atoi()将字符串转换成整型数的函数 原形：int atoi(const char *s) 功能：把s所指向的字符串转换成int类型。 s格式为:符号数字 返回值：字符串的转换值。若出错则返回0。 头文件：stdlib.h 函数5。atol()将字符串转换成长整型数的函数 原形：long atol(const char *s)
几种构造辅助函数的方法及应用
几种构造辅助函数的方法及应用 许生虎 （西北师范大学数学系，甘肃 兰州 730070） 摘 要：在对数学命题的观察和分析基础上给出了构造辅助函数的方法，举例说明了寻求 辅助函数的几种方法及在解题中的作用。 关键词：辅助函数 弧弦差法 原函数法 几何直观法 微分方程法 1. 引言 在解题过程中，根据问题的条件与结论的特点，通过逆向分析、综合运用数学的基本概念和原理，经过深入思考、缜密的观察和广泛的联想，构造出一个与问题有关的辅助函数，通过对函数特征的考查达到解决问题的目的，这种解决问题的方法叫做构造辅助函数法。 构造函数方法在许多命题证明中的应用，使问题得以解决，如在微分中值定理、泰勒公式、中值点存在性、不等式等证明。但构造辅助函数方法的内涵十分丰富没有固定的模式和方法，构造过程充分体现了数学的发现、类比、逆向思维及归纳、猜想、分析与化归思想。但如何通过构造，构造怎样的辅助函数给出命题的证明，是很难理解的问题之一，本文通过一些典型例题归纳、分析和总结常见的构造辅助函数方法及应用。 2. 构造辅助函数的七中方法 2.1“逆向思维法” 例1： 设()x f 在[]1,0 上可微，且满足 ()()?=2 1 21dx x xf f ，证明在][1,0内至少有一点θ，
使()() θθθf f -='. 证明:由所证明的结论出发,结合已知条件,探寻恰当的辅助函数. 将()() θθθf f '变为()()0='?+θθθf f ,联想到()[]()()θθθθf f x xf x '?+='=,可考虑 辅助函数 ()()[].1,0,∈=x x xf x F 因为()()ξξf f =1 , 而对于()x F ,有()()ξξξf F =,()().11f F = 所以,()()1F F =ξ ,由罗尔定理知,至少存在一点()1,ξθ∈,使得()0='θF 即:()() θθθf f -='. 证毕 2.2 原函数法 在微分中值定理(尤其是罗尔定理)求解介值(或零点)问题时要证明的结论往往是某一个函数的导函数的零点,因此可通过不定积分反求出原函数作为辅助函数,用此法构造辅助函数的具体步骤如下: (1)将要证的结论中的;)(0x x 换或ξ (2)通过恒等变换,将结论化为易积分(或易消除导数符号)的形式; (3)用观察法或凑微分法求出原函数(必要时可在等式两端同乘以非零的积分因子),为简便起见,可将积分常数取为零;
用Winhex手动修复分区表以提取数据
一、初步应用——双分区恢复实例及分析 （一）、现场重现： 提示，切勿随意使用自己的硬盘进行试验，切记试验前保存重要数据。对于移动硬盘，损坏往往发生于硬盘传输数据中断电。现在我将一个有问题的移动硬盘接到电脑上，在“计算机管理”-->“磁盘工具”中我们可以看到这个未被初始化的磁盘显示为黑色（打开磁盘工具时它会提示你要初始化，不理它，点“取消”），在“计算机”中也找不到这个磁盘。 （二）、手动修复： （阅读有困难的朋友可以先读完第三节再回过头来看这一节，本节的另一个作用是让新手对Winhex界面有一个初步了解） 1、打开Winhex-->菜单栏-->选择“工具”-->打开磁盘（F9）-->选择要修复的硬盘，这里是HD2。
2、打开之后图中显示从0000H-->01ffH（16进制）之间的数据全部为0。 现在我从一个运转良好的硬盘分区表中将0000H-->01bdH之间的数据复制并粘贴到损坏硬盘的相应位置。
操作步骤为：在良好硬盘中拉选0000-->01bd之间的区块，被选中区块呈亮蓝色；复制选块； 接下来在损坏硬盘中拉选相应区域，将光标定位至0000；右键-->编辑-->粘贴板数据-->写入。将01fe，01ff填写为55AA，到这里一定保存。 点击黄色区域的图标并转移至63号扇区菜单“视图”-->模板管理（Alt+F12）-->NTFS引导扇区。
打开如下图，并记录黄色方框内的两个数值（63和63777986）
63+63777986+1=63778050，跳转至63778050扇区。 稍微向下滚动一点，看到那个粉色框标识出的55AA了嘛？往前找到黄色框内的部分，显示为3F 00 00 00，将其进行反向排列，变为00 00 00 3F于是3F(十六进制)=63(十进制)——我们称这个数为相对偏移量。 接下来跳转至63778050+63=63778113扇区，我们又发现了一个EB开头的扇区 再次选择菜单“视图”-->模板管理（Alt+F12）-->主引导记录NTFS引导扇区。打开如下图，同样记录一下黄色方框中的数值（63和92518271）
C语言中常见的功能函数
C语言中常见的功能函数（应掌握的编程） 1、两个变量值的交换 void exchang(float *x,float *y) /*形参为两个变量的地铁（指针）*/ {float z; z=*x; *x=*y; *y=z; } void main() {float a,b; scanf(“%f%f”,&a,&b); exchang(&a,&b); /*因为形参是指针，所以实参必须给变量的地址，不能给变量名*/ printf(“a=%f,b=%f”,a,b); } 2、判断一个整数的奇偶 int jou(int n) /*如果是奇数返回1，否则返回0*/ { if(n%2==0) return 0; return 1; } 3、小写字符转换成大写字符 根据实参传给形参的字母，判断是否是小写字母，如果是小写字母，则转换成大写字母，否则不进行转换，函数返回转换后或原来的字符。 本函数仿照toupper()库函数的功能编写（toupper(c) 是将变量c字母转换成大写字母，如果不是小写字母不转换）。 char toupper1(char ch) {if(ch>=?a?&&ch<=?z?) ch-=32; /*小写字母比对应的大写字母ASCII码值大32*/ return ch; } 4、判断一个字符是否是字母（或数字） 根据实参传给形参的字符，判断是否是字母（或数字），如果是字母（或数字）返回1，否则返回0。此函数是根据库函数isalpha()（或isdigit()）来编写的。 int isalpha1(char ch) /*判断是否是字母*/ {if(ch>=?A?&&ch<=?Z?||ch>=?a?&&ch<=?z?) return 1; else return 0; } int isdigit1(char ch) /*判断是否是数字字符*/ {if(ch>=?0?&&ch<=?9?) return 1; else return 0; } 5、根据学生成绩，返回其等级 char fun(float cj) {char c; switch((int)cj/10) {case 10:
winhex数据恢复完整图文教程
winhex 数据恢复分类：硬恢复和软恢复。所谓硬恢复就是硬盘出现物理性损伤，比如有盘体坏道、电路板芯片烧毁、盘体异响，等故障，由此所导致的普通用户不容易取出里面数据，那么我们将它修好，同时又保留里面的数据或后来恢复里面的数据，这些都叫数据恢复，只不过这些故障有容易的和困难的之分；所谓软恢复，就是硬盘本身没有物理损伤，而是由于人为或者病毒破坏所造成的数据丢失（比如误格式化，误分区），那么这样的数据恢复就叫软恢复。 这里呢，我们主要介绍软恢复，因为硬恢复还需要购买一些工具设备（比如pc3000,电烙铁，各种芯片、电路板），而且还需要懂一点点电路基础，我们这里所讲到的所有的知识，涉及面广，层次深，既有数据结构原理，为我们手工准确恢复数据提供依据，又有各种数据恢复软件的使用方法及技巧，为我们快速恢复数据提供便利，而且所有软件均为网上下载，不需要我们投资一分钱。 数据恢复的前提：数据不能被二次破坏、覆盖！ 关于数码与码制： 关于二进制、十六进制、八进制它们之间的转换我不想多说，因为他对我们数据恢复来说帮助不大，而且很容易把我们绕晕。如果你感兴趣想多了解一些，可以到百度里面去搜一下，这方面资料已经很多了，就不需要我再多说了。 数据恢复我们主要用十六进制编辑器：Winhex （数据恢复首选软件） 我们先了解一下数据结构： 下面是一个分了三个区的整个硬盘的数据结构 MBR，即主引导纪录，位于整个硬盘的0柱面0磁道1扇区，共占用了63个扇区，但实际只使用了1个扇区（512字节）。在总共512字节的主引导记录中，MBR又可分为三部分：第一部分：引导代码，占用了446个字节；第二部分：分区表，占用了64字节；第三部分：55AA，结束标志，占用了两个字节。后面我们要说的用winhex软件来恢复误分区，主要就是恢复第二部分：分区表。 引导代码的作用：就是让硬盘具备可以引导的功能。如果引导代码丢失，分区表还在，那么这个硬盘作为从盘所有分区数据都还在，只是这个硬盘自己不能够用来启动进系统了。如果要恢复引导代码，可以用DOS下的命令：FDISK /MBR；这个命令只是用来恢复引导代码，不会引起分区改变，丢失数据。另外，也可以用工具软件，比如DISKGEN、WINHEX等。 但分区表如果丢失，后果就是整个硬盘一个分区没有，就好象刚买来一个新硬盘没有分过区一样。是很多病毒喜欢破坏的区域。 EBR，也叫做扩展MBR（Extended MBR）。因为主引导记录MBR最多只能描述4个分区项，如果想要在一个硬盘上分多于4个区，就要采用扩展MBR的办法。 MBR、EBR是分区产生的。 比如MBR和EBR各都占用63个扇区，C盘占用1435329个扇区……那么数据结构如下表： 而每一个分区又由DBR、FAT1、FAT2、DIR、DATA5部分组成：比如C 盘的数据结构： Winhex Winhex是使用最多的一款工具软件，是在Windows下运行的十六进制编辑软件，此软件功能非常强大，有完善的分区管理功能和文件管理功能，能自动分析分区链和文件簇链，能对硬盘进行不同方式不同程度的备份，甚至克隆整个硬盘；它能够编辑任何一种文件类型的二进制内容（用十六进制显示）其磁盘编辑器可以编辑物理磁盘或逻辑磁盘的任意扇区，是手工恢复数据的首选工具软件。 首先要安装Winhex，安装完了就可以启动winhex了，启动画面如下：首先出现的是启动中心对话框。
用DiskGenius原DiskMan修复损坏的硬盘分区
前段时间，遇到有两个硬盘不能正常打开。都是挂在同一台电脑上，忽然停电后就不能打开 了。通过查看原来分区表已损坏，连PQmagic都不能进去，总是提示错误就退出。只好用DiskGenius(下面称为DG)来试一下，以前试用过这个软件，觉得分区功能比PQmagic还好，我试过一Vista系统的硬盘，PQ不能识别分区，但DiskGenius就可以轻松搞掂，那时用的 还是Dos版本。但以下介绍的是使用Windows版本，而且都是在Windos XP下运行修复。第一步，下载DiskGenius 在一台可以正常开机启动Window XP的电脑上在网上下载DiskGenius，我用的是 V3.1.0412 Beta 3的版本；也可以把程序复制到Ｕ盘，通过Ｕ盘复制到另一台正常的Windows系统电脑上面，关掉电脑。 第二步，将需要维修的硬盘挂在电脑上 可以将损坏的硬盘设置为从盘或者是另外一个硬盘线(IDE2)的主盘。要记住是IDE2的接口上，不然启动不了系统的。 第三步，开机启动WindowsXP，启动DiskGenius 看到HD1:Maxtor这个设备吗？这就是要修复的硬盘空间是60G，可以看到磁盘显示空闲，什么数据都没有，分区表已经损坏了。 下一步，搜索分区 点击修复的硬盘，然后点击工具栏上的“搜索分区”按钮，让程序自动搜索分区表。 第四步，设置搜索分区参数
由于是整个硬盘的分区都丢失，所以搜索范围选择“整个硬盘”，搜索方式选择“自动”，然后点击“开始搜索”按钮。 第五步，确认搜索分区 当点击“开始搜索”按钮后，程序会自动查找硬盘损坏的分区，并将修复结果显示出来。第六步，查看分区文件信息
C语言常用IO函数
一些比较常用的io函数,总结了一下,一块贴出来了 stdin标准输入流 stdout标准输出流 stderr标准错误流 字符IO函数 1.int getchar() 说明：从stdin读取1个字符 返回值：成功，返回该字符；出错，返回EOF； 2.int fgetc(FILE fp) 说明：功能同getchar，默认从文件fp读取； 返回值：成功，返回该字符；出错，返回EOF； 可以重定向 3.int getc(FILE fp) 说明：功能与fgetc相同，但getc既可以被用作 函数实现，也可以被用作宏实现，并且它的编码效率 可能会更高. 可以重定向 4.int putchar(int ch) 说明：向stdout输出字符ch； 返回值：成功，返回该字符；出错，返回EOF； 5.int fputc(int c,FILE fp) 说明：功能同putchar，默认向fp输出字符ch； 返回值：成功，返回该字符；出错，返回EOF； 6.int putc(int c,FILE fp) 说明：功能与fputc相同，但putc与getc一样既可能被用作 函数实现，也可能被用作宏实现，并且它的编码效率可能会更高；可以重定向 字符串IO函数 1.char gets(char str) 说明：从stdin读取字符串(不包括'n')写入到字符串str中； 返回值：成功，返回str首地址；错误，返回NULL； 2.char fgets(char str,int N,FILE fp) 说明：默认从文件fp中读取N个字符(包括'n')写入到字符串str中，
如果实际输入字符串小于N,fgets自动添加'n'， 返回值：成功，返回字符串首地址；错误或遇到EOF，返回NULL；可以重定向 3.int puts(const char str) 说明：向stdout输出字符串str，然受输出一个'n'， 返回值：成功，返回非负值；错误，EOF； 4.int fputs(const char str,FILE fp) 说明：功能同puts，默认向文件fp写入字符串str； 返回值：成功，返回非负值；错误，EOF； 可以重定向 格式化IO函数 1.int scanf(const char format,...) 说明：根据format从stdin格式化读取N个值，并输入到... 返回值：成功，返回读取的项数；出错，返回EOF 2.int fscanf(FILE fp,const char format,...) 说明：功能同scanf，默认从文件fp读取， 返回值：成功，返回读取的项数；出错或遇到文件尾，返回EOF 可以重定向 3.int sscanf(const char buf,const char format,...) 说明：根据format从buf格式化读取N个值，并输入到... 返回值：成功，返回读取的项数；出错，返回EOF 4.int printf(const char format,...) 说明：根据format格式化数据，并输出到stdout 返回值成功，返回输出字符数；错误，返回负数； 5.int fprintf(FILE fp,const char format,...) 说明：功能同printf，默认向文件fp写入; 可以重定向 6.int sprintf(char buf,const char format,...) 说明：根据format格式化数据，并输出到buf， 返回值：成功，返回输出字符数；错误，返回负数
巧用WinHex找回消失的分区数据
巧用WinHex找回消失的分区数据 由于我是个对磁盘空间过敏的人，每当磁盘空间少到几百兆，就会想办法删掉不用的软件，时间一长，系统会变的千疮百孔，直到有一天实在无法忍受，决定重装系统，麻烦极了。与是想用Guest做个系统映象，没想到人世间最痛苦的事情发生了。 我有两个物理硬盘，主盘分了两个区，分别为一个C盘，一个E盘，所以把Guest这个软件放到第二个硬盘D盘的根目录下。重起进入DOS进入到软件的画面，不管三七二十一，玩玩再说。好奇的我直接选择第一项功能: To Disk，经过乱七八糟的英文提示后，毅然点了OK按扭，接下来两个硬盘开始狂响，我突然意识到事情不对，强行重起动后，打开资源管理器，点下D盘，发现已经空白一片了。天哪！我的软件！我的游戏！我的一切！我浑身冒汗，好像做梦一样，早知道……咦，对了！好像WinHex有打开磁盘的功能，只要知道一些文件的开头标记，兴许能恢复一些文件。 小提示：硬盘修复是一个高危险的操作，在https://www.360docs.net/doc/08620125.html,/YingJian/200808/107.ht m一文中介绍了硬盘主引导记录等多种不同故障的处理方法，希望对大家有所参考。 幸好WinHex装到C盘上了，启动后选“OpenDisk”打开D盘，在WinHex子窗口的表格内共有三个列，最左边的是偏移值，相当于行号；中间显示的是16进制代码，右边是每组代码对应显示的文字。因为无论是那种格式的文件开头都会有特定的标记，所以只要知道对应的代码就能知到文件的类型。由于我D盘上大部分是RAR压缩格式的文件，所以我先用WinRar创建一个RAR文件，再用WinHex打开，在右边开头显示出Rar!字样（图1），对应的16进制的值就是“52 61 72 21”，一同选中后按“Ctrl+Shift+C”把这串代码复制到剪贴板，然后切换到刚才打开D盘的窗口，依次选择“Search >> Find Hex Values”，按“Ctrl+V”或在输入框内点右键选择“粘贴”，确认无误后点“OK”开始搜索。 因为D盘容量是10GB，所以要经过漫长的等待。为了恢复文件，等他个一二天也值得。好在只用了5分钟的时间，便找到了第一个数值完全相同的一串代码，双击选种开头部分。 在此说明一下，有些软件在结尾也会有标记，比如ZIP格式，但RAR的结尾没有标记，这并不是件坏事，打个比方，一个RAR文件有300K大小，如果你选择的数值超过了300K而达到10M，那么用WinRar压时还可将原内容完整解压出来，只是在后面提示“非预期的压缩包结尾!”，你想一下，不可能多个RAR文件都会按顺序排列，中间可能会加入其它的文件，比如E XE文件，所以如果恢复的是RAR文件，选多点也无所谓，就怕选少了。所以下面我还要按F3键继续查找。
0磁道损坏修复的两种方法
0磁道损坏修复的两种方法 “0”磁道处于硬盘上一个非常重要的位置，硬盘的主引导记录区(MBR)就在这个位置上。MBR位于硬盘的0磁道0柱面1扇区，其中存放着硬盘主引导程序和硬盘分区表。在总共512字节的硬盘主引导记录扇区中，446字节属于硬盘主引导程序，64字节属于硬盘分区表(DPT)，两个字节(55 AA)属于分区结束标志。由此可见，“0”磁道一旦受损，将使硬盘的主引导程序和分区表信息遭到严重破坏，从而导致硬盘无法自举。 “0”磁道处于硬盘上一个非常重要的位置，硬盘的主引导记录区(MBR)就在这个位置上。MBR位于硬盘的0磁道0柱面1扇区，其中存放着硬盘主引导程序和硬盘分区表。在总共512字节的硬盘主引导记录扇区中，446字节属于硬盘主引导程序，64字节属于硬盘分区表(DPT)，两个字节(55 AA)属于分区结束标志。由此可见，“0”磁道一旦受损，将使硬盘的主引导程序和分区表信息遭到严重破坏，从而导致硬盘无法自举。“0”磁道损坏也属于硬盘坏道，只不过由于它的位置太重要，因而一旦遭到破坏，就会产生严重的后果。 1.硬盘“0”磁道损坏后的症状 当硬盘“0”磁道损坏后：系统自检能通过，但启动时，分区丢失或者C盘目录丢失，硬盘出现有规律的“咯吱……咯吱”的寻道声，运行SCANDISK扫描C盘，在第一簇出现一个红色的“B”；Fdisk 等分区软件
找不到硬盘、利用低版本的DM进行分区时，程序“死”在0磁道上；在进行“Format C：”时，屏幕提示0磁道损坏或无休止地执行读命令“Track 0 Bad”。 2.解决硬盘“0”磁道损坏的思路 磁头总是把“0”磁道作为寻道的基准点，如果“0”磁道出现物理损坏，磁头定位机构会因找不到“0”磁道，使硬盘自举失败。因此，在解决硬盘“0”磁道损坏问题时，一般都采取“以1代0”的方法，也就是在划分硬盘分区时，重新定义“0”磁道，将原来的“1”磁道定义为逻辑上的“0”磁道，避开已损坏的“0”磁道。 3.通过工具软件解决硬盘“0”磁道损坏 (1)通过DM万用版解决 首先从网上下载DM万用版并制作好DM启动软盘，然后执行DM 并进入其主界面。在主界面中按下Alt+M组合键进入DM的高级模式，将光标定位到“(E)dit/View partitions”(编辑/查看分区)选项，按回车键之后，程序要求选择需要修复的硬盘，选中硬盘，按回车便进入了该硬盘的分区查看界面。如图１所示。 在分区列表框中选中“1”号分区，此时上面的分区信息栏将显示该分区信息，例如分区格式、容量、开始的柱面、结束的柱面等。此时需要记住开始柱面中的“0”和结束柱面序号“2489”。保持光标定位在1号分区上，然后按下Del键删除该分区，在出现的确认删除分区的界面中选择“Yes”并回车，此时1号分区便删除了。
C语言常用函数手册
1.分类函数,所在函数库为ctype.h int isalpha(int ch) 若ch是字母('A'-'Z','a'-'z')返回非0值,否则返回0 int isalnum(int ch) 若ch是字母('A'-'Z','a'-'z')或数字('0'-'9'),返回非0值,否则返回0 int isascii(int ch) 若ch是字符(ASCII码中的0-127)返回非0值,否则返回0 int iscntrl(int ch) 若ch是作废字符(0x7F)或普通控制字符(0x00-0x1F) 返回非0值,否则返回0 int isdigit(int ch) 若ch是数字('0'-'9')返回非0值,否则返回0 int isgraph(int ch) 若ch是可打印字符(不含空格)(0x21-0x7E)返回非0值,否则返回0 int islower(int ch) 若ch是小写字母('a'-'z')返回非0值,否则返回0 int isprint(int ch) 若ch是可打印字符(含空格)(0x20-0x7E)返回非0值,否则返回0 int ispunct(int ch) 若ch是标点字符(0x00-0x1F)返回非0值,否则返回0 int isspace(int ch) 若ch是空格(' '),水平制表符('\t'),回车符('\r'), 走纸换行('\f'),垂直制表符('\v'),换行符('\n') 返回非0值,否则返回0 int isupper(int ch) 若ch是大写字母('A'-'Z')返回非0值,否则返回0 int isxdigit(int ch) 若ch是16进制数('0'-'9','A'-'F','a'-'f')返回非0值, 否则返回0 int tolower(int ch) 若ch是大写字母('A'-'Z')返回相应的小写字母('a'-'z') int toupper(int ch) 若ch是小写字母('a'-'z')返回相应的大写字母('A'-'Z') 2.数学函数,所在函数库为math.h、stdlib.h、string.h、float.h int abs(int i) 返回整型参数i的绝对值 double cabs(struct complex znum) 返回复数znum的绝对值 double fabs(double x) 返回双精度参数x的绝对值 long labs(long n) 返回长整型参数n的绝对值 double exp(double x) 返回指数函数ex的值 double frexp(double value,int *eptr) 返回value=x*2n中x的值,n存贮在eptr中double ldexp(double value,int exp); 返回value*2exp的值 double log(double x) 返回logex的值 double log10(double x) 返回log10x的值 double pow(double x,double y) 返回xy的值 double pow10(int p) 返回10p的值 double sqrt(double x) 返回+√x的值 double acos(double x) 返回x的反余弦cos-1(x)值,x为弧度 double asin(double x) 返回x的反正弦sin-1(x)值,x为弧度 double atan(double x) 返回x的反正切tan-1(x)值,x为弧度 double atan2(double y,double x) 返回y/x的反正切tan-1(x)值,y的x为弧度double cos(double x) 返回x的余弦cos(x)值,x为弧度 double sin(double x) 返回x的正弦sin(x)值,x为弧度 double tan(double x) 返回x的正切tan(x)值,x为弧度 double cosh(double x) 返回x的双曲余弦cosh(x)值,x为弧度 double sinh(double x) 返回x的双曲正弦sinh(x)值,x为弧度
中值定理构造辅助函数
微分中值定理证明中辅助函数的构造 1 原函数法 此法是将结论变形并向罗尔定理的结论靠拢，凑出适当的原函数作为辅助函数，主要思想分为四点：(1)将要证的结论中的ξ换成x ；(2)通过恒等变形将结论化为易消除导数符号的形式；(3)用观察法或积分法求出原函数（等式中不含导数符号），并取积分常数为零；(4)移项使等式一边为零，另一边即为所求辅助函数()F x ． 例1：证明柯西中值定理． 分析：在柯西中值定理的结论 ()()'()()()'()f b f a f g b g a g ξξ-=-中令x ξ=，得()()'()()()'()f b f a f x g b g a g x -=-，先变形为()()'()'()()()f b f a g x f x g b g a -=-再两边同时积分得 ()()()()()() f b f a g x f x C g b g a -=+-，令0C =，有() ()()()0()()f b f a f x g x g b g a --=-故()()()()()()() f b f a F x f x g x g b g a -=--为所求辅助函数． 例2：若0a ,1a ,2a ,…,n a 是使得1200231 n a a a a n ++++=+…的实数．证明方程20120n n a a x a x a x ++++=…在（0，1）内至少有一实根． 证：由于2231120120()231n n n n a a a a a x a x a x dx a x x x x C n +++++=++++++?…… 并且这一积分结果与题设条件和要证明的结论有联系，所以设 231120()231 n n a a a F x a x x x x n +=+++++…（取0C =），则 1）()F x 在[0，1]上连续 2）()F x 在（0，1）内可导 3）(0)F =0， 120(1)0231 n a a a F a n =++++=+… 故()F x 满足罗尔定理的条件，由罗尔定理，存在(0,1)ξ∈使'()0F ξ=，即231120()'0231 n n x a a a a x x x x n ξ+=++++=+…亦即20120n n a a a a ξξξ++++=…．
winhex恢复U盘分区
Winhex恢复U盘分区 你是否因为U盘提示格式化而为舍不得U盘里的重要数据感到舍不得呢？你是否因为没有正确使用U盘导致U盘数据丢失而后悔呢？你是否因为病毒如期U盘而烦恼呢？U盘在今天的非常普遍使用的，而使用的人群虽然很多，所以不会正确使用U盘的人群也越发多了起来。不正确的使用U盘会导致U盘损坏以至于U盘里的重要数据文件丢失。今天就来教大家怎样使用winhex软件恢复U盘的分区。 1.首先插入损坏的U盘（提示需要格式化，这里我们不能格式化，否则将无法找回数据） 2.使用winhex软件打开U盘的物理存储介质
3.查看错误位置（此处为U盘的分区表被破坏了，所以导致U盘需要格式化才能用） 4.查看U盘的引导扇区模板
5.根据引导扇区的模板看出此分区的起始扇区和结束扇区，然后通过计算器的程序员模式算出起始扇区和结束扇区的16进制数 1.打开winhex软件自带的计算器
2.点击查看》程序员 3.点击十进制》输入起始扇区号
4.点击十六进制》得出数值的十六进制数（NTFS格式需要在结束扇区上加一位数） 5.填写十六进制数时需要倒着填写[例如我们计算出的十六进制数为80 0 ，那 么填写到起始扇区的时候应填写为00 08 00 00 (起始扇区和结束扇区的位置需填写四个字节) ]
6.填写硬盘的分区表信息 1.跳转到U盘的0扇区（每个字节两位数） 2.0x01BE处写入80 3.0x01BF处写入00 4.0x01C0处写入00 5.0x01C1处写入00 6.0x01C2处写入硬盘的格式（NTFS:07 FAT32：0B exFAT:07） 7.0x01C3处写入FE 8.0x01C4处写入FF 9.0x01C5处写入FF 10.0x01C6至0x01C9处写入分区的起始扇区的十六进制数 11.0x01CA至0x01CD处写入分区的结束扇区的十六进制数 12.CTEL+S保存修改，之后重新拔插U盘即可
用Diskedit修复分区表(图解教程)
用Diskedit修复分区表(图解教程) 我们经常在使用电脑的时候，由于非法操作和病毒的侵袭会导致系统不能引启，驱动器丢失，其实就是有可能就是分区表损坏，遇到这种情况，很多朋友都选择重新分区格式化磁盘加以修复，其实这种“修复”算不得什么修复，因为之前的内容不存在了，这就是为什么很多朋友当硬件工作者只会装系统的原因。诚然，分区装系统的确在很多时候就是最简单且笼统的方式，但是，如果我们一个盘里有很多重要的资料的时候，我们还会这样做吗？今天我们来讲一下硬盘的分区表，来看看解决上面遇到的办法我们有无最佳的有效的解决途径。 其实分表区就是存在在磁盘里的0柱面0磁头1扇区的位置，是一个64字节大小的“数据库”该数据库里记录了，我们分区的一些起始信息，很显然他的重要性勿庸至疑，你想想“盘”都没有了，盘里的资料还存在吗？可见分区表的一重要性了。今天我们一起来探奧秘。 我们用诺顿的diskedit来打开一个硬盘的分区表来一窥其貌。 简单地说一下这个软件的使用方法，虽说英文但一点也不困难。这是一个纯DOS软件如果你也想用的话，你可以点此下载，把它放到你的启动盘里到DOS下面去运行它。 该界面的大意是。你正工作在一个只读的模式下，如果你要更改些什么东西，你必须到tools里去掉只读属性。在此我们按任意键跳过。接着看下面。按ALT+O选择你要编辑查看的磁盘。 这里要注意以下几点。左边一定要选择你的硬盘，而右边要选择你的物理磁盘。如图所示
分区表一般位于硬盘某柱面的0磁头1扇区.要判定是不是分区表,就看其后紧邻的两个是不是 “55AA”,若是,则为分区表．如图所示，其实这就是分区表，我们说过分区表只有64字节所以，只有80到55AA这一段为我们的分区表，我们要讲解的就是这一部分。 好了，既然认识了分区表我们就来看看，常见的分区表故障吧。这个表里的信息是用16进程的方式进行表示的，有一定的死记硬背形。 我们先来看第一个标识符80.这是一个活动分区标志符,有的书中称为激活分区，有的叫主DOS分区有的叫引导分区一般性况下（这个情况起码有99%，你的系统在C盘吗？在哪么就属于此例），如果这个标识被篡改。相信你的电脑一定不能启动，这个标识符为固定的，如果你的硬盘里存在系统，这个是一定存在的。我们故意把它改成其00试一下，有什么故障。前面我们说过，要修改分区表，你得去掉只读属性。我们来去掉。ALT+T指打开tools,选N，用空格去掉Read only前面的叉，按ALT+S保存。于是你就可以随地更改你的分区表了。